# _a : accuracy
# _p : precision
-$VERSION = '1.46';
-require 5.005;
+$VERSION = '1.58';
+require 5.006002;
require Exporter;
-@ISA = qw(Exporter Math::BigInt);
+@ISA = qw/Math::BigInt/;
+@EXPORT_OK = qw/bpi/;
use strict;
# $_trap_inf/$_trap_nan are internal and should never be accessed from outside
my $class = "Math::BigFloat";
use overload
-'<=>' => sub { $_[2] ?
+'<=>' => sub { my $rc = $_[2] ?
ref($_[0])->bcmp($_[1],$_[0]) :
- ref($_[0])->bcmp($_[0],$_[1])},
+ ref($_[0])->bcmp($_[0],$_[1]);
+ $rc = 1 unless defined $rc;
+ $rc <=> 0;
+ },
+# we need '>=' to get things like "1 >= NaN" right:
+'>=' => sub { my $rc = $_[2] ?
+ ref($_[0])->bcmp($_[1],$_[0]) :
+ ref($_[0])->bcmp($_[0],$_[1]);
+ # if there was a NaN involved, return false
+ return '' unless defined $rc;
+ $rc >= 0;
+ },
'int' => sub { $_[0]->as_number() }, # 'trunc' to bigint
;
# accessor methods instead.
# class constants, use Class->constant_name() to access
-$round_mode = 'even'; # one of 'even', 'odd', '+inf', '-inf', 'zero' or 'trunc'
+# one of 'even', 'odd', '+inf', '-inf', 'zero', 'trunc' or 'common'
+$round_mode = 'even';
$accuracy = undef;
$precision = undef;
$div_scale = 40;
$downgrade = undef;
# the package we are using for our private parts, defaults to:
# Math::BigInt->config()->{lib}
-my $MBI = 'Math::BigInt::Calc';
+my $MBI = 'Math::BigInt::FastCalc';
# are NaNs ok? (otherwise it dies when encountering an NaN) set w/ config()
$_trap_nan = 0;
my $LOG_2 =
'0.6931471805599453094172321214581765680755001343602552541206800094933936220';
my $LOG_2_A = length($LOG_2)-1;
-my $HALF = '0.5'; # made into an object if necc.
+my $HALF = '0.5'; # made into an object if nec.
##############################################################################
# the old code had $rnd_mode, so we need to support it, too
BEGIN
{
- # when someone set's $rnd_mode, we catch this and check the value to see
+ # when someone sets $rnd_mode, we catch this and check the value to see
# whether it is valid or not.
- $rnd_mode = 'even'; tie $rnd_mode, 'Math::BigFloat';
+ $rnd_mode = 'even'; tie $rnd_mode, 'Math::BigFloat';
+
+ # we need both of them in this package:
+ *as_int = \&as_number;
}
##############################################################################
# valid method aliases for AUTOLOAD
my %methods = map { $_ => 1 }
qw / fadd fsub fmul fdiv fround ffround fsqrt fmod fstr fsstr fpow fnorm
- fint facmp fcmp fzero fnan finf finc fdec flog ffac
- fceil ffloor frsft flsft fone flog froot
+ fint facmp fcmp fzero fnan finf finc fdec ffac fneg
+ fceil ffloor frsft flsft fone flog froot fexp
/;
- # valid method's that can be hand-ed up (for AUTOLOAD)
+ # valid methods that can be handed up (for AUTOLOAD)
my %hand_ups = map { $_ => 1 }
qw / is_nan is_inf is_negative is_positive is_pos is_neg
- accuracy precision div_scale round_mode fneg fabs fnot
+ accuracy precision div_scale round_mode fabs fnot
objectify upgrade downgrade
bone binf bnan bzero
+ bsub
/;
- sub method_alias { exists $methods{$_[0]||''}; }
- sub method_hand_up { exists $hand_ups{$_[0]||''}; }
+ sub _method_alias { exists $methods{$_[0]||''}; }
+ sub _method_hand_up { exists $hand_ups{$_[0]||''}; }
}
##############################################################################
my $self = {}; bless $self, $class;
# shortcut for bigints and its subclasses
- if ((ref($wanted)) && (ref($wanted) ne $class))
+ if ((ref($wanted)) && UNIVERSAL::can( $wanted, "as_number"))
{
$self->{_m} = $wanted->as_number()->{value}; # get us a bigint copy
$self->{_e} = $MBI->_zero();
$self->{sign} = $wanted->sign();
return $self->bnorm();
}
- # got string
+ # else: got a string or something maskerading as number (with overload)
+
# handle '+inf', '-inf' first
- if ($wanted =~ /^[+-]?inf$/)
+ if ($wanted =~ /^[+-]?inf\z/)
{
return $downgrade->new($wanted) if $downgrade;
+ $self->{sign} = $wanted; # set a default sign for bstr()
+ return $self->binf($wanted);
+ }
+
+ # shortcut for simple forms like '12' that neither have trailing nor leading
+ # zeros
+ if ($wanted =~ /^([+-]?)([1-9][0-9]*[1-9])$/)
+ {
$self->{_e} = $MBI->_zero();
$self->{_es} = '+';
- $self->{_m} = $MBI->_zero();
- $self->{sign} = $wanted;
- $self->{sign} = '+inf' if $self->{sign} eq 'inf';
- return $self->bnorm();
+ $self->{sign} = $1 || '+';
+ $self->{_m} = $MBI->_new($2);
+ return $self->round(@r) if !$downgrade;
}
my ($mis,$miv,$mfv,$es,$ev) = Math::BigInt::_split($wanted);
($self->{_e}, $self->{_es}) =
_e_sub ($self->{_e}, $len, $self->{_es}, '+');
}
- $self->{sign} = $$mis;
-
- # we can only have trailing zeros on the mantissa of $$mfv eq ''
- if (CORE::length($$mfv) == 0)
+ # we can only have trailing zeros on the mantissa if $$mfv eq ''
+ else
{
- my $zeros = $MBI->_zeros($self->{_m}); # correct for trailing zeros
+ # Use a regexp to count the trailing zeros in $$miv instead of _zeros()
+ # because that is faster, especially when _m is not stored in base 10.
+ my $zeros = 0; $zeros = CORE::length($1) if $$miv =~ /[1-9](0*)$/;
if ($zeros != 0)
{
my $z = $MBI->_new($zeros);
+ # turn '120e2' into '12e3'
$MBI->_rsft ( $self->{_m}, $z, 10);
- _e_add ( $self->{_e}, $z, $self->{_es}, '+');
+ ($self->{_e}, $self->{_es}) =
+ _e_add ( $self->{_e}, $z, $self->{_es}, '+');
}
}
+ $self->{sign} = $$mis;
+
# for something like 0Ey, set y to 1, and -0 => +0
+ # Check $$miv for being '0' and $$mfv eq '', because otherwise _m could not
+ # have become 0. That's faster than to call $MBI->_is_zero().
$self->{sign} = '+', $self->{_e} = $MBI->_one()
- if $MBI->_is_zero($self->{_m});
+ if $$miv eq '0' and $$mfv eq '';
+
return $self->round(@r) if !$downgrade;
}
# if downgrade, inf, NaN or integers go down
sub copy
{
- my ($c,$x);
+ # if two arguments, the first one is the class to "swallow" subclasses
if (@_ > 1)
{
- # if two arguments, the first one is the class to "swallow" subclasses
- ($c,$x) = @_;
- }
- else
- {
- $x = shift;
- $c = ref($x);
+ my $self = bless {
+ sign => $_[1]->{sign},
+ _es => $_[1]->{_es},
+ _m => $MBI->_copy($_[1]->{_m}),
+ _e => $MBI->_copy($_[1]->{_e}),
+ }, $_[0] if @_ > 1;
+
+ $self->{_a} = $_[1]->{_a} if defined $_[1]->{_a};
+ $self->{_p} = $_[1]->{_p} if defined $_[1]->{_p};
+ return $self;
}
- return unless ref($x); # only for objects
- my $self = {}; bless $self,$c;
+ my $self = bless {
+ sign => $_[0]->{sign},
+ _es => $_[0]->{_es},
+ _m => $MBI->_copy($_[0]->{_m}),
+ _e => $MBI->_copy($_[0]->{_e}),
+ }, ref($_[0]);
- $self->{sign} = $x->{sign};
- $self->{_es} = $x->{_es};
- $self->{_m} = $MBI->_copy($x->{_m});
- $self->{_e} = $MBI->_copy($x->{_e});
- $self->{_a} = $x->{_a} if defined $x->{_a};
- $self->{_p} = $x->{_p} if defined $x->{_p};
+ $self->{_a} = $_[0]->{_a} if defined $_[0]->{_a};
+ $self->{_p} = $_[0]->{_p} if defined $_[0]->{_p};
$self;
}
# return (later set?) configuration data as hash ref
my $class = shift || 'Math::BigFloat';
+ if (@_ == 1 && ref($_[0]) ne 'HASH')
+ {
+ my $cfg = $class->SUPER::config();
+ return $cfg->{$_[0]};
+ }
+
my $cfg = $class->SUPER::config(@_);
# now we need only to override the ones that are different from our parent
# (ref to BFLOAT or num_str ) return num_str
# Convert number from internal format to (non-scientific) string format.
# internal format is always normalized (no leading zeros, "-0" => "+0")
- my ($self,$x) = ref($_[0]) ? (ref($_[0]),$_[0]) : objectify(1,@_);
+ my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
if ($x->{sign} !~ /^[+-]$/)
{
# (ref to BFLOAT or num_str ) return num_str
# Convert number from internal format to scientific string format.
# internal format is always normalized (no leading zeros, "-0E0" => "+0E0")
- my ($self,$x) = ref($_[0]) ? (ref($_[0]),$_[0]) : objectify(1,@_);
+ my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
if ($x->{sign} !~ /^[+-]$/)
{
##############################################################################
# public stuff (usually prefixed with "b")
+sub bneg
+ {
+ # (BINT or num_str) return BINT
+ # negate number or make a negated number from string
+ my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
+
+ return $x if $x->modify('bneg');
+
+ # for +0 dont negate (to have always normalized +0). Does nothing for 'NaN'
+ $x->{sign} =~ tr/+-/-+/ unless ($x->{sign} eq '+' && $MBI->_is_zero($x->{_m}));
+ $x;
+ }
+
# tels 2001-08-04
# XXX TODO this must be overwritten and return NaN for non-integer values
# band(), bior(), bxor(), too
# return result as BFLOAT
# set up parameters
- my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+ my ($self,$x,$y,@r) = (ref($_[0]),@_);
# objectify is costly, so avoid it
if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
{
- ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
+ ($self,$x,$y,@r) = objectify(2,@_);
}
+
+ return $x if $x->modify('badd');
# inf and NaN handling
if (($x->{sign} !~ /^[+-]$/) || ($y->{sign} !~ /^[+-]$/))
return $x;
}
- return $upgrade->badd($x,$y,$a,$p,$r) if defined $upgrade &&
+ return $upgrade->badd($x,$y,@r) if defined $upgrade &&
((!$x->isa($self)) || (!$y->isa($self)));
+ $r[3] = $y; # no push!
+
# speed: no add for 0+y or x+0
- return $x->bround($a,$p,$r) if $y->is_zero(); # x+0
+ return $x->bround(@r) if $y->is_zero(); # x+0
if ($x->is_zero()) # 0+y
{
# make copy, clobbering up x (modify in place!)
$x->{_es} = $y->{_es};
$x->{_m} = $MBI->_copy($y->{_m});
$x->{sign} = $y->{sign} || $nan;
- return $x->round($a,$p,$r,$y);
+ return $x->round(@r);
}
# take lower of the two e's and adapt m1 to it to match m2
}
# delete trailing zeros, then round
- $x->bnorm()->round($a,$p,$r,$y);
+ $x->bnorm()->round(@r);
}
# sub bsub is inherited from Math::BigInt!
# increment arg by one
my ($self,$x,@r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+ return $x if $x->modify('binc');
+
if ($x->{_es} eq '-')
{
return $x->badd($self->bone(),@r); # digits after dot
# decrement arg by one
my ($self,$x,@r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+ return $x if $x->modify('bdec');
+
if ($x->{_es} eq '-')
{
return $x->badd($self->bone('-'),@r); # digits after dot
{
my ($self,$x,$base,$a,$p,$r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+ return $x if $x->modify('blog');
+
# $base > 0, $base != 1; if $base == undef default to $base == e
# $x >= 0
# also takes care of the "error in _find_round_parameters?" case
return $x->bnan() if $x->{sign} ne '+' || $x->is_zero();
-
# no rounding at all, so must use fallback
if (scalar @params == 0)
{
}
return $x->bzero(@params) if $x->is_one();
- # base not defined => base == Euler's constant e
+ # base not defined => base == Euler's number e
if (defined $base)
{
# make object, since we don't feed it through objectify() to still get the
local $Math::BigFloat::downgrade = undef;
# upgrade $x if $x is not a BigFloat (handle BigInt input)
+ # XXX TODO: rebless!
if (!$x->isa('Math::BigFloat'))
{
$x = Math::BigFloat->new($x);
if ($done == 0)
{
- # first calculate the log to base e (using reduction by 10 (and probably 2))
+ # base is undef, so base should be e (Euler's number), so first calculate the
+ # log to base e (using reduction by 10 (and probably 2)):
$self->_log_10($x,$scale);
# and if a different base was requested, convert it
$x;
}
+sub _len_to_steps
+ {
+ # Given D (digits in decimal), compute N so that N! (N factorial) is
+ # at least D digits long. D should be at least 50.
+ my $d = shift;
+
+ # two constants for the Ramanujan estimate of ln(N!)
+ my $lg2 = log(2 * 3.14159265) / 2;
+ my $lg10 = log(10);
+
+ # D = 50 => N => 42, so L = 40 and R = 50
+ my $l = 40; my $r = $d;
+
+ # Otherwise this does not work under -Mbignum and we do not yet have "no bignum;" :(
+ $l = $l->numify if ref($l);
+ $r = $r->numify if ref($r);
+ $lg2 = $lg2->numify if ref($lg2);
+ $lg10 = $lg10->numify if ref($lg10);
+
+ # binary search for the right value (could this be written as the reverse of lg(n!)?)
+ while ($r - $l > 1)
+ {
+ my $n = int(($r - $l) / 2) + $l;
+ my $ramanujan =
+ int(($n * log($n) - $n + log( $n * (1 + 4*$n*(1+2*$n)) ) / 6 + $lg2) / $lg10);
+ $ramanujan > $d ? $r = $n : $l = $n;
+ }
+ $l;
+ }
+
+sub bnok
+ {
+ # Calculate n over k (binomial coefficient or "choose" function) as integer.
+ # set up parameters
+ my ($self,$x,$y,@r) = (ref($_[0]),@_);
+
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$x,$y,@r) = objectify(2,@_);
+ }
+
+ return $x if $x->modify('bnok');
+
+ return $x->bnan() if $x->is_nan() || $y->is_nan();
+ return $x->binf() if $x->is_inf();
+
+ my $u = $x->as_int();
+ $u->bnok($y->as_int());
+
+ $x->{_m} = $u->{value};
+ $x->{_e} = $MBI->_zero();
+ $x->{_es} = '+';
+ $x->{sign} = '+';
+ $x->bnorm(@r);
+ }
+
+sub bexp
+ {
+ # Calculate e ** X (Euler's number to the power of X)
+ my ($self,$x,$a,$p,$r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+
+ return $x if $x->modify('bexp');
+
+ return $x->binf() if $x->{sign} eq '+inf';
+ return $x->bzero() if $x->{sign} eq '-inf';
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($x,@params) = $x->_find_round_parameters($a,$p,$r);
+
+ # also takes care of the "error in _find_round_parameters?" case
+ return $x if $x->{sign} eq 'NaN';
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # P = undef
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it's not enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ return $x->bone(@params) if $x->is_zero();
+
+ if (!$x->isa('Math::BigFloat'))
+ {
+ $x = Math::BigFloat->new($x);
+ $self = ref($x);
+ }
+
+ # when user set globals, they would interfere with our calculation, so
+ # disable them and later re-enable them
+ no strict 'refs';
+ my $abr = "$self\::accuracy"; my $ab = $$abr; $$abr = undef;
+ my $pbr = "$self\::precision"; my $pb = $$pbr; $$pbr = undef;
+ # we also need to disable any set A or P on $x (_find_round_parameters took
+ # them already into account), since these would interfere, too
+ delete $x->{_a}; delete $x->{_p};
+ # need to disable $upgrade in BigInt, to avoid deep recursion
+ local $Math::BigInt::upgrade = undef;
+ local $Math::BigFloat::downgrade = undef;
+
+ my $x_org = $x->copy();
+
+ # We use the following Taylor series:
+
+ # x x^2 x^3 x^4
+ # e = 1 + --- + --- + --- + --- ...
+ # 1! 2! 3! 4!
+
+ # The difference for each term is X and N, which would result in:
+ # 2 copy, 2 mul, 2 add, 1 inc, 1 div operations per term
+
+ # But it is faster to compute exp(1) and then raising it to the
+ # given power, esp. if $x is really big and an integer because:
+
+ # * The numerator is always 1, making the computation faster
+ # * the series converges faster in the case of x == 1
+ # * We can also easily check when we have reached our limit: when the
+ # term to be added is smaller than "1E$scale", we can stop - f.i.
+ # scale == 5, and we have 1/40320, then we stop since 1/40320 < 1E-5.
+ # * we can compute the *exact* result by simulating bigrat math:
+
+ # 1 1 gcd(3,4) = 1 1*24 + 1*6 5
+ # - + - = ---------- = --
+ # 6 24 6*24 24
+
+ # We do not compute the gcd() here, but simple do:
+ # 1 1 1*24 + 1*6 30
+ # - + - = --------- = --
+ # 6 24 6*24 144
+
+ # In general:
+ # a c a*d + c*b and note that c is always 1 and d = (b*f)
+ # - + - = ---------
+ # b d b*d
+
+ # This leads to: which can be reduced by b to:
+ # a 1 a*b*f + b a*f + 1
+ # - + - = --------- = -------
+ # b b*f b*b*f b*f
+
+ # The first terms in the series are:
+
+ # 1 1 1 1 1 1 1 1 13700
+ # -- + -- + -- + -- + -- + --- + --- + ---- = -----
+ # 1 1 2 6 24 120 720 5040 5040
+
+ # Note that we cannot simple reduce 13700/5040 to 685/252, but must keep A and B!
+
+ if ($scale <= 75)
+ {
+ # set $x directly from a cached string form
+ $x->{_m} = $MBI->_new(
+ "27182818284590452353602874713526624977572470936999595749669676277240766303535476");
+ $x->{sign} = '+';
+ $x->{_es} = '-';
+ $x->{_e} = $MBI->_new(79);
+ }
+ else
+ {
+ # compute A and B so that e = A / B.
+
+ # After some terms we end up with this, so we use it as a starting point:
+ my $A = $MBI->_new("90933395208605785401971970164779391644753259799242");
+ my $F = $MBI->_new(42); my $step = 42;
+
+ # Compute how many steps we need to take to get $A and $B sufficiently big
+ my $steps = _len_to_steps($scale - 4);
+# print STDERR "# Doing $steps steps for ", $scale-4, " digits\n";
+ while ($step++ <= $steps)
+ {
+ # calculate $a * $f + 1
+ $A = $MBI->_mul($A, $F);
+ $A = $MBI->_inc($A);
+ # increment f
+ $F = $MBI->_inc($F);
+ }
+ # compute $B as factorial of $steps (this is faster than doing it manually)
+ my $B = $MBI->_fac($MBI->_new($steps));
+
+# print "A ", $MBI->_str($A), "\nB ", $MBI->_str($B), "\n";
+
+ # compute A/B with $scale digits in the result (truncate, not round)
+ $A = $MBI->_lsft( $A, $MBI->_new($scale), 10);
+ $A = $MBI->_div( $A, $B );
+
+ $x->{_m} = $A;
+ $x->{sign} = '+';
+ $x->{_es} = '-';
+ $x->{_e} = $MBI->_new($scale);
+ }
+
+ # $x contains now an estimate of e, with some surplus digits, so we can round
+ if (!$x_org->is_one())
+ {
+ # raise $x to the wanted power and round it in one step:
+ $x->bpow($x_org, @params);
+ }
+ else
+ {
+ # else just round the already computed result
+ delete $x->{_a}; delete $x->{_p};
+ # shortcut to not run through _find_round_parameters again
+ if (defined $params[0])
+ {
+ $x->bround($params[0],$params[2]); # then round accordingly
+ }
+ else
+ {
+ $x->bfround($params[1],$params[2]); # then round accordingly
+ }
+ }
+ if ($fallback)
+ {
+ # clear a/p after round, since user did not request it
+ delete $x->{_a}; delete $x->{_p};
+ }
+ # restore globals
+ $$abr = $ab; $$pbr = $pb;
+
+ $x; # return modified $x
+ }
+
sub _log
{
# internal log function to calculate ln() based on Taylor series.
# in case of $x == 1, result is 0
return $x->bzero() if $x->is_one();
+ # XXX TODO: rewrite this in a similiar manner to bexp()
+
# http://www.efunda.com/math/taylor_series/logarithmic.cfm?search_string=log
# u = x-1, v = x+1
# if we truncated $over and $below we might get 0.12345. Does this matter
# for the end result? So we give $over and $below 4 more digits to be
# on the safe side (unscientific error handling as usual... :+D
-
+
$next = $over->copy->bround($scale+4)->bdiv(
$below->copy->bmul($factor)->bround($scale+4),
$scale);
$steps++; print "step $steps = $x\n" if $steps % 10 == 0;
}
}
- $x->bmul($f); # $x *= 2
print "took $steps steps\n" if DEBUG;
+ $x->bmul($f); # $x *= 2
}
sub _log_10
# and then "correcting" the result to the proper one. Modifies $x in place.
my ($self,$x,$scale) = @_;
- # taking blog() from numbers greater than 10 takes a *very long* time, so we
+ # Taking blog() from numbers greater than 10 takes a *very long* time, so we
# break the computation down into parts based on the observation that:
- # blog(x*y) = blog(x) + blog(y)
- # We set $y here to multiples of 10 so that $x is below 1 (the smaller $x is
- # the faster it get's, especially because 2*$x takes about 10 times as long,
- # so by dividing $x by 10 we make it at least factor 100 faster...)
-
- # The same observation is valid for numbers smaller than 0.1 (e.g. computing
- # log(1) is fastest, and the farther away we get from 1, the longer it takes)
- # so we also 'break' this down by multiplying $x with 10 and subtract the
+ # blog(X*Y) = blog(X) + blog(Y)
+ # We set Y here to multiples of 10 so that $x becomes below 1 - the smaller
+ # $x is the faster it gets. Since 2*$x takes about 10 times as
+ # long, we make it faster by about a factor of 100 by dividing $x by 10.
+
+ # The same observation is valid for numbers smaller than 0.1, e.g. computing
+ # log(1) is fastest, and the further away we get from 1, the longer it takes.
+ # So we also 'break' this down by multiplying $x with 10 and subtract the
# log(10) afterwards to get the correct result.
- # calculate nr of digits before dot
+ # To get $x even closer to 1, we also divide by 2 and then use log(2) to
+ # correct for this. For instance if $x is 2.4, we use the formula:
+ # blog(2.4 * 2) == blog (1.2) + blog(2)
+ # and thus calculate only blog(1.2) and blog(2), which is faster in total
+ # than calculating blog(2.4).
+
+ # In addition, the values for blog(2) and blog(10) are cached.
+
+ # Calculate nr of digits before dot:
my $dbd = $MBI->_num($x->{_e});
$dbd = -$dbd if $x->{_es} eq '-';
$dbd += $MBI->_len($x->{_m});
# we can use the cached value in these cases
if ($scale <= $LOG_10_A)
{
- $x->bzero(); $x->badd($LOG_10);
+ $x->bzero(); $x->badd($LOG_10); # modify $x in place
$calc = 0; # no need to calc, but round
}
+ # if we can't use the shortcut, we continue normally
}
else
{
# we can use the cached value in these cases
if ($scale <= $LOG_2_A)
{
- $x->bzero(); $x->badd($LOG_2);
+ $x->bzero(); $x->badd($LOG_2); # modify $x in place
$calc = 0; # no need to calc, but round
}
+ # if we can't use the shortcut, we continue normally
}
}
my $l_10; # value of ln(10) to A of $scale
my $l_2; # value of ln(2) to A of $scale
+ my $two = $self->new(2);
+
# $x == 2 => 1, $x == 13 => 2, $x == 0.1 => 0, $x == 0.01 => -1
# so don't do this shortcut for 1 or 0
if (($dbd > 1) || ($dbd < 0))
}
else
{
- # else: slower, compute it (but don't cache it, because it could be big)
+ # else: slower, compute and cache result
# also disable downgrade for this code path
local $Math::BigFloat::downgrade = undef;
- $l_10 = $self->new(10)->blog(undef,$scale); # scale+4, actually
+
+ # shorten the time to calculate log(10) based on the following:
+ # log(1.25 * 8) = log(1.25) + log(8)
+ # = log(1.25) + log(2) + log(2) + log(2)
+
+ # first get $l_2 (and possible compute and cache log(2))
+ $LOG_2 = $self->new($LOG_2,undef,undef) unless ref $LOG_2;
+ if ($scale <= $LOG_2_A)
+ {
+ # use cached value
+ $l_2 = $LOG_2->copy(); # copy() for the mul below
+ }
+ else
+ {
+ # else: slower, compute and cache result
+ $l_2 = $two->copy(); $self->_log($l_2, $scale); # scale+4, actually
+ $LOG_2 = $l_2->copy(); # cache the result for later
+ # the copy() is for mul below
+ $LOG_2_A = $scale;
+ }
+
+ # now calculate log(1.25):
+ $l_10 = $self->new('1.25'); $self->_log($l_10, $scale); # scale+4, actually
+
+ # log(1.25) + log(2) + log(2) + log(2):
+ $l_10->badd($l_2);
+ $l_10->badd($l_2);
+ $l_10->badd($l_2);
+ $LOG_10 = $l_10->copy(); # cache the result for later
+ # the copy() is for mul below
+ $LOG_10_A = $scale;
}
$dbd-- if ($dbd > 1); # 20 => dbd=2, so make it dbd=1
$l_10->bmul( $self->new($dbd)); # log(10) * (digits_before_dot-1)
$HALF = $self->new($HALF) unless ref($HALF);
my $twos = 0; # default: none (0 times)
- my $two = $self->new(2);
- while ($x->bacmp($HALF) <= 0)
+ while ($x->bacmp($HALF) <= 0) # X <= 0.5
{
$twos--; $x->bmul($two);
}
- while ($x->bacmp($two) >= 0)
+ while ($x->bacmp($two) >= 0) # X >= 2
{
$twos++; $x->bdiv($two,$scale+4); # keep all digits
}
- # $twos > 0 => did mul 2, < 0 => did div 2 (never both)
- # calculate correction factor based on ln(2)
+ # $twos > 0 => did mul 2, < 0 => did div 2 (but we never did both)
+ # So calculate correction factor based on ln(2):
if ($twos != 0)
{
$LOG_2 = $self->new($LOG_2,undef,undef) unless ref $LOG_2;
if ($scale <= $LOG_2_A)
{
# use cached value
- $l_2 = $LOG_2->copy(); # copy for mul
+ $l_2 = $LOG_2->copy(); # copy() for the mul below
}
else
{
- # else: slower, compute it (but don't cache it, because it could be big)
+ # else: slower, compute and cache result
# also disable downgrade for this code path
local $Math::BigFloat::downgrade = undef;
- $l_2 = $two->blog(undef,$scale); # scale+4, actually
+ $l_2 = $two->copy(); $self->_log($l_2, $scale); # scale+4, actually
+ $LOG_2 = $l_2->copy(); # cache the result for later
+ # the copy() is for mul below
+ $LOG_2_A = $scale;
}
$l_2->bmul($twos); # * -2 => subtract, * 2 => add
}
$self->_log($x,$scale); # need to do the "normal" way
$x->badd($l_10) if defined $l_10; # correct it by ln(10)
$x->badd($l_2) if defined $l_2; # and maybe by ln(2)
+
# all done, $x contains now the result
+ $x;
}
sub blcm
my ($self,@arg) = objectify(0,@_);
my $x = $self->new(shift @arg);
- while (@arg) { $x = _lcm($x,shift @arg); }
+ while (@arg) { $x = Math::BigInt::__lcm($x,shift @arg); }
$x;
}
-sub bgcd
- {
- # (BFLOAT or num_str, BFLOAT or num_str) return BINT
+sub bgcd
+ {
+ # (BINT or num_str, BINT or num_str) return BINT
# does not modify arguments, but returns new object
- # GCD -- Euclids algorithm Knuth Vol 2 pg 296
-
- my ($self,@arg) = objectify(0,@_);
- my $x = $self->new(shift @arg);
- while (@arg) { $x = _gcd($x,shift @arg); }
+
+ my $y = shift;
+ $y = __PACKAGE__->new($y) if !ref($y);
+ my $self = ref($y);
+ my $x = $y->copy()->babs(); # keep arguments
+
+ return $x->bnan() if $x->{sign} !~ /^[+-]$/ # x NaN?
+ || !$x->is_int(); # only for integers now
+
+ while (@_)
+ {
+ my $t = shift; $t = $self->new($t) if !ref($t);
+ $y = $t->copy()->babs();
+
+ return $x->bnan() if $y->{sign} !~ /^[+-]$/ # y NaN?
+ || !$y->is_int(); # only for integers now
+
+ # greatest common divisor
+ while (! $y->is_zero())
+ {
+ ($x,$y) = ($y->copy(), $x->copy()->bmod($y));
+ }
+
+ last if $x->is_one();
+ }
$x;
}
# return true if arg (BFLOAT or num_str) is an integer
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
- return 1 if ($x->{sign} =~ /^[+-]$/) && # NaN and +-inf aren't
- $x->{_es} eq '+'; # 1e-1 => no integer
- 0;
+ (($x->{sign} =~ /^[+-]$/) && # NaN and +-inf aren't
+ ($x->{_es} eq '+')) ? 1 : 0; # 1e-1 => no integer
}
sub is_zero
# return true if arg (BFLOAT or num_str) is zero
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
- return 1 if $x->{sign} eq '+' && $MBI->_is_zero($x->{_m});
- 0;
+ ($x->{sign} eq '+' && $MBI->_is_zero($x->{_m})) ? 1 : 0;
}
sub is_one
my ($self,$x,$sign) = ref($_[0]) ? (undef,@_) : objectify(1,@_);
$sign = '+' if !defined $sign || $sign ne '-';
- return 1
- if ($x->{sign} eq $sign &&
- $MBI->_is_zero($x->{_e}) && $MBI->_is_one($x->{_m}));
- 0;
+
+ ($x->{sign} eq $sign &&
+ $MBI->_is_zero($x->{_e}) &&
+ $MBI->_is_one($x->{_m}) ) ? 1 : 0;
}
sub is_odd
# return true if arg (BFLOAT or num_str) is odd or false if even
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
- return 1 if ($x->{sign} =~ /^[+-]$/) && # NaN & +-inf aren't
- ($MBI->_is_zero($x->{_e}) && $MBI->_is_odd($x->{_m}));
- 0;
+ (($x->{sign} =~ /^[+-]$/) && # NaN & +-inf aren't
+ ($MBI->_is_zero($x->{_e})) &&
+ ($MBI->_is_odd($x->{_m}))) ? 1 : 0;
}
sub is_even
# return true if arg (BINT or num_str) is even or false if odd
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
- return 0 if $x->{sign} !~ /^[+-]$/; # NaN & +-inf aren't
- return 1 if ($x->{_es} eq '+' # 123.45 is never
- && $MBI->_is_even($x->{_m})); # but 1200 is
- 0;
+ (($x->{sign} =~ /^[+-]$/) && # NaN & +-inf aren't
+ ($x->{_es} eq '+') && # 123.45 isn't
+ ($MBI->_is_even($x->{_m}))) ? 1 : 0; # but 1200 is
}
-sub bmul
+sub bmul
{
- # multiply two numbers -- stolen from Knuth Vol 2 pg 233
- # (BINT or num_str, BINT or num_str) return BINT
+ # multiply two numbers
# set up parameters
- my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+ my ($self,$x,$y,@r) = (ref($_[0]),@_);
# objectify is costly, so avoid it
if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
{
- ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
+ ($self,$x,$y,@r) = objectify(2,@_);
}
+ return $x if $x->modify('bmul');
+
return $x->bnan() if (($x->{sign} eq $nan) || ($y->{sign} eq $nan));
# inf handling
return $x->binf() if ($x->{sign} =~ /^-/ && $y->{sign} =~ /^-/);
return $x->binf('-');
}
- # handle result = 0
- return $x->bzero() if $x->is_zero() || $y->is_zero();
- return $upgrade->bmul($x,$y,$a,$p,$r) if defined $upgrade &&
+ return $upgrade->bmul($x,$y,@r) if defined $upgrade &&
((!$x->isa($self)) || (!$y->isa($self)));
# aEb * cEd = (a*c)E(b+d)
$MBI->_mul($x->{_m},$y->{_m});
($x->{_e}, $x->{_es}) = _e_add($x->{_e}, $y->{_e}, $x->{_es}, $y->{_es});
+ $r[3] = $y; # no push!
+
# adjust sign:
$x->{sign} = $x->{sign} ne $y->{sign} ? '-' : '+';
- return $x->bnorm()->round($a,$p,$r,$y);
+ $x->bnorm->round(@r);
}
-sub bdiv
- {
- # (dividend: BFLOAT or num_str, divisor: BFLOAT or num_str) return
- # (BFLOAT,BFLOAT) (quo,rem) or BFLOAT (only rem)
-
+sub bmuladd
+ {
+ # multiply two numbers and add the third to the result
+
# set up parameters
- my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+ my ($self,$x,$y,$z,@r) = (ref($_[0]),@_);
# objectify is costly, so avoid it
if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
{
- ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
+ ($self,$x,$y,$z,@r) = objectify(3,@_);
}
- return $self->_div_inf($x,$y)
- if (($x->{sign} !~ /^[+-]$/) || ($y->{sign} !~ /^[+-]$/) || $y->is_zero());
-
- # x== 0 # also: or y == 1 or y == -1
- return wantarray ? ($x,$self->bzero()) : $x if $x->is_zero();
-
- # upgrade ?
- return $upgrade->bdiv($upgrade->new($x),$y,$a,$p,$r) if defined $upgrade;
-
- # we need to limit the accuracy to protect against overflow
- my $fallback = 0;
- my (@params,$scale);
- ($x,@params) = $x->_find_round_parameters($a,$p,$r,$y);
+ return $x if $x->modify('bmuladd');
- return $x if $x->is_nan(); # error in _find_round_parameters?
+ return $x->bnan() if (($x->{sign} eq $nan) ||
+ ($y->{sign} eq $nan) ||
+ ($z->{sign} eq $nan));
- # no rounding at all, so must use fallback
- if (scalar @params == 0)
- {
- # simulate old behaviour
- $params[0] = $self->div_scale(); # and round to it as accuracy
- $scale = $params[0]+4; # at least four more for proper round
- $params[2] = $r; # round mode by caller or undef
- $fallback = 1; # to clear a/p afterwards
- }
- else
+ # inf handling
+ if (($x->{sign} =~ /^[+-]inf$/) || ($y->{sign} =~ /^[+-]inf$/))
{
- # the 4 below is empirical, and there might be cases where it is not
- # enough...
- $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ return $x->bnan() if $x->is_zero() || $y->is_zero();
+ # result will always be +-inf:
+ # +inf * +/+inf => +inf, -inf * -/-inf => +inf
+ # +inf * -/-inf => -inf, -inf * +/+inf => -inf
+ return $x->binf() if ($x->{sign} =~ /^\+/ && $y->{sign} =~ /^\+/);
+ return $x->binf() if ($x->{sign} =~ /^-/ && $y->{sign} =~ /^-/);
+ return $x->binf('-');
}
- my $rem; $rem = $self->bzero() if wantarray;
+ return $upgrade->bmul($x,$y,@r) if defined $upgrade &&
+ ((!$x->isa($self)) || (!$y->isa($self)));
- $y = $self->new($y) unless $y->isa('Math::BigFloat');
+ # aEb * cEd = (a*c)E(b+d)
+ $MBI->_mul($x->{_m},$y->{_m});
+ ($x->{_e}, $x->{_es}) = _e_add($x->{_e}, $y->{_e}, $x->{_es}, $y->{_es});
- my $lx = $MBI->_len($x->{_m}); my $ly = $MBI->_len($y->{_m});
+ $r[3] = $y; # no push!
+
+ # adjust sign:
+ $x->{sign} = $x->{sign} ne $y->{sign} ? '-' : '+';
+
+ # z=inf handling (z=NaN handled above)
+ $x->{sign} = $z->{sign}, return $x if $z->{sign} =~ /^[+-]inf$/;
+
+ # take lower of the two e's and adapt m1 to it to match m2
+ my $e = $z->{_e};
+ $e = $MBI->_zero() if !defined $e; # if no BFLOAT?
+ $e = $MBI->_copy($e); # make copy (didn't do it yet)
+
+ my $es;
+
+ ($e,$es) = _e_sub($e, $x->{_e}, $z->{_es} || '+', $x->{_es});
+
+ my $add = $MBI->_copy($z->{_m});
+
+ if ($es eq '-') # < 0
+ {
+ $MBI->_lsft( $x->{_m}, $e, 10);
+ ($x->{_e},$x->{_es}) = _e_add($x->{_e}, $e, $x->{_es}, $es);
+ }
+ elsif (!$MBI->_is_zero($e)) # > 0
+ {
+ $MBI->_lsft($add, $e, 10);
+ }
+ # else: both e are the same, so just leave them
+
+ if ($x->{sign} eq $z->{sign})
+ {
+ # add
+ $x->{_m} = $MBI->_add($x->{_m}, $add);
+ }
+ else
+ {
+ ($x->{_m}, $x->{sign}) =
+ _e_add($x->{_m}, $add, $x->{sign}, $z->{sign});
+ }
+
+ # delete trailing zeros, then round
+ $x->bnorm()->round(@r);
+ }
+
+sub bdiv
+ {
+ # (dividend: BFLOAT or num_str, divisor: BFLOAT or num_str) return
+ # (BFLOAT,BFLOAT) (quo,rem) or BFLOAT (only rem)
+
+ # set up parameters
+ my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
+ }
+
+ return $x if $x->modify('bdiv');
+
+ return $self->_div_inf($x,$y)
+ if (($x->{sign} !~ /^[+-]$/) || ($y->{sign} !~ /^[+-]$/) || $y->is_zero());
+
+ # x== 0 # also: or y == 1 or y == -1
+ return wantarray ? ($x,$self->bzero()) : $x if $x->is_zero();
+
+ # upgrade ?
+ return $upgrade->bdiv($upgrade->new($x),$y,$a,$p,$r) if defined $upgrade;
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my (@params,$scale);
+ ($x,@params) = $x->_find_round_parameters($a,$p,$r,$y);
+
+ return $x if $x->is_nan(); # error in _find_round_parameters?
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it is not
+ # enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ my $rem; $rem = $self->bzero() if wantarray;
+
+ $y = $self->new($y) unless $y->isa('Math::BigFloat');
+
+ my $lx = $MBI->_len($x->{_m}); my $ly = $MBI->_len($y->{_m});
$scale = $lx if $lx > $scale;
$scale = $ly if $ly > $scale;
my $diff = $ly - $lx;
$scale += $diff if $diff > 0; # if lx << ly, but not if ly << lx!
-
- # cases like $x /= $x (but not $x /= $y!) were wrong due to modifying $x
- # twice below)
- require Scalar::Util;
- if (Scalar::Util::refaddr($x) == Scalar::Util::refaddr($y))
+
+ # already handled inf/NaN/-inf above:
+
+ # check that $y is not 1 nor -1 and cache the result:
+ my $y_not_one = !($MBI->_is_zero($y->{_e}) && $MBI->_is_one($y->{_m}));
+
+ # flipping the sign of $y will also flip the sign of $x for the special
+ # case of $x->bsub($x); so we can catch it below:
+ my $xsign = $x->{sign};
+ $y->{sign} =~ tr/+-/-+/;
+
+ if ($xsign ne $x->{sign})
{
- $x->bone(); # x/x => 1, rem 0
+ # special case of $x /= $x results in 1
+ $x->bone(); # "fixes" also sign of $y, since $x is $y
}
else
{
-
+ # correct $y's sign again
+ $y->{sign} =~ tr/+-/-+/;
+ # continue with normal div code:
+
# make copy of $x in case of list context for later reminder calculation
- if (wantarray && !$y->is_one())
+ if (wantarray && $y_not_one)
{
$rem = $x->copy();
}
$x->{sign} = $x->{sign} ne $y->sign() ? '-' : '+';
# check for / +-1 ( +/- 1E0)
- if (!$y->is_one())
+ if ($y_not_one)
{
# promote BigInts and it's subclasses (except when already a BigFloat)
$y = $self->new($y) unless $y->isa('Math::BigFloat');
if (wantarray)
{
- if (!$y->is_one())
+ if ($y_not_one)
{
$rem->bmod($y,@params); # copy already done
}
($self,$x,$y,$a,$p,$r) = objectify(2,@_);
}
+ return $x if $x->modify('bmod');
+
# handle NaN, inf, -inf
if (($x->{sign} !~ /^[+-]$/) || ($y->{sign} !~ /^[+-]$/))
{
return $x->bnan() if $x->is_zero();
return $x;
}
- return $x->bzero() if $y->is_one() || $x->is_zero();
+
+ return $x->bzero() if $x->is_zero()
+ || ($x->is_int() &&
+ # check that $y == +1 or $y == -1:
+ ($MBI->_is_zero($y->{_e}) && $MBI->_is_one($y->{_m})));
my $cmp = $x->bacmp($y); # equal or $x < $y?
return $x->bzero($a,$p) if $cmp == 0; # $x == $y => result 0
($self,$x,$y,$a,$p,$r) = objectify(2,@_);
}
+ return $x if $x->modify('broot');
+
# NaN handling: $x ** 1/0, x or y NaN, or y inf/-inf or y == 0
return $x->bnan() if $x->{sign} !~ /^\+/ || $y->is_zero() ||
$y->{sign} !~ /^\+$/;
# calculate square root
my ($self,$x,$a,$p,$r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+ return $x if $x->modify('bsqrt');
+
return $x->bnan() if $x->{sign} !~ /^[+]/; # NaN, -inf or < 0
return $x if $x->{sign} eq '+inf'; # sqrt(inf) == inf
return $x->round($a,$p,$r) if $x->is_zero() || $x->is_one();
# objectify is costly, so avoid it
($self,$x,@r) = objectify(1,@_) if !ref($x);
- return $x if $x->{sign} eq '+inf'; # inf => inf
+ # inf => inf
+ return $x if $x->modify('bfac') || $x->{sign} eq '+inf';
+
return $x->bnan()
if (($x->{sign} ne '+') || # inf, NaN, <0 etc => NaN
($x->{_es} ne '+')); # digits after dot?
$x->{_e} = $MBI->_zero(); # normalize
$x->{_es} = '+';
}
- $MBI->_fac($x->{_m}); # calculate factorial
- $x->bnorm()->round(@r); # norm again and round result
+ $MBI->_fac($x->{_m}); # calculate factorial
+ $x->bnorm()->round(@r); # norm again and round result
+ }
+
+sub _pow
+ {
+ # Calculate a power where $y is a non-integer, like 2 ** 0.3
+ my ($x,$y,@r) = @_;
+ my $self = ref($x);
+
+ # if $y == 0.5, it is sqrt($x)
+ $HALF = $self->new($HALF) unless ref($HALF);
+ return $x->bsqrt(@r,$y) if $y->bcmp($HALF) == 0;
+
+ # Using:
+ # a ** x == e ** (x * ln a)
+
+ # u = y * ln x
+ # _ _
+ # Taylor: | u u^2 u^3 |
+ # x ** y = 1 + | --- + --- + ----- + ... |
+ # |_ 1 1*2 1*2*3 _|
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($x,@params) = $x->_find_round_parameters(@r);
+
+ return $x if $x->is_nan(); # error in _find_round_parameters?
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # disable P
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r[2]; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it is not
+ # enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ # when user set globals, they would interfere with our calculation, so
+ # disable them and later re-enable them
+ no strict 'refs';
+ my $abr = "$self\::accuracy"; my $ab = $$abr; $$abr = undef;
+ my $pbr = "$self\::precision"; my $pb = $$pbr; $$pbr = undef;
+ # we also need to disable any set A or P on $x (_find_round_parameters took
+ # them already into account), since these would interfere, too
+ delete $x->{_a}; delete $x->{_p};
+ # need to disable $upgrade in BigInt, to avoid deep recursion
+ local $Math::BigInt::upgrade = undef;
+
+ my ($limit,$v,$u,$below,$factor,$next,$over);
+
+ $u = $x->copy()->blog(undef,$scale)->bmul($y);
+ $v = $self->bone(); # 1
+ $factor = $self->new(2); # 2
+ $x->bone(); # first term: 1
+
+ $below = $v->copy();
+ $over = $u->copy();
+
+ $limit = $self->new("1E-". ($scale-1));
+ #my $steps = 0;
+ while (3 < 5)
+ {
+ # we calculate the next term, and add it to the last
+ # when the next term is below our limit, it won't affect the outcome
+ # anymore, so we stop:
+ $next = $over->copy()->bdiv($below,$scale);
+ last if $next->bacmp($limit) <= 0;
+ $x->badd($next);
+ # calculate things for the next term
+ $over *= $u; $below *= $factor; $factor->binc();
+
+ last if $x->{sign} !~ /^[-+]$/;
+
+ #$steps++;
+ }
+
+ # shortcut to not run through _find_round_parameters again
+ if (defined $params[0])
+ {
+ $x->bround($params[0],$params[2]); # then round accordingly
+ }
+ else
+ {
+ $x->bfround($params[1],$params[2]); # then round accordingly
+ }
+ if ($fallback)
+ {
+ # clear a/p after round, since user did not request it
+ delete $x->{_a}; delete $x->{_p};
+ }
+ # restore globals
+ $$abr = $ab; $$pbr = $pb;
+ $x;
+ }
+
+sub bpow
+ {
+ # (BFLOAT or num_str, BFLOAT or num_str) return BFLOAT
+ # compute power of two numbers, second arg is used as integer
+ # modifies first argument
+
+ # set up parameters
+ my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
+ }
+
+ return $x if $x->modify('bpow');
+
+ return $x->bnan() if $x->{sign} eq $nan || $y->{sign} eq $nan;
+ return $x if $x->{sign} =~ /^[+-]inf$/;
+
+ # cache the result of is_zero
+ my $y_is_zero = $y->is_zero();
+ return $x->bone() if $y_is_zero;
+ return $x if $x->is_one() || $y->is_one();
+
+ my $x_is_zero = $x->is_zero();
+ return $x->_pow($y,$a,$p,$r) if !$x_is_zero && !$y->is_int(); # non-integer power
+
+ my $y1 = $y->as_number()->{value}; # make MBI part
+
+ # if ($x == -1)
+ if ($x->{sign} eq '-' && $MBI->_is_one($x->{_m}) && $MBI->_is_zero($x->{_e}))
+ {
+ # if $x == -1 and odd/even y => +1/-1 because +-1 ^ (+-1) => +-1
+ return $MBI->_is_odd($y1) ? $x : $x->babs(1);
+ }
+ if ($x_is_zero)
+ {
+ #return $x->bone() if $y_is_zero;
+ return $x if $y->{sign} eq '+'; # 0**y => 0 (if not y <= 0)
+ # 0 ** -y => 1 / (0 ** y) => 1 / 0! (1 / 0 => +inf)
+ return $x->binf();
+ }
+
+ my $new_sign = '+';
+ $new_sign = $MBI->_is_odd($y1) ? '-' : '+' if $x->{sign} ne '+';
+
+ # calculate $x->{_m} ** $y and $x->{_e} * $y separately (faster)
+ $x->{_m} = $MBI->_pow( $x->{_m}, $y1);
+ $x->{_e} = $MBI->_mul ($x->{_e}, $y1);
+
+ $x->{sign} = $new_sign;
+ $x->bnorm();
+ if ($y->{sign} eq '-')
+ {
+ # modify $x in place!
+ my $z = $x->copy(); $x->bone();
+ return scalar $x->bdiv($z,$a,$p,$r); # round in one go (might ignore y's A!)
+ }
+ $x->round($a,$p,$r,$y);
+ }
+
+sub bmodpow
+ {
+ # takes a very large number to a very large exponent in a given very
+ # large modulus, quickly, thanks to binary exponentation. Supports
+ # negative exponents.
+ my ($self,$num,$exp,$mod,@r) = objectify(3,@_);
+
+ return $num if $num->modify('bmodpow');
+
+ # check modulus for valid values
+ return $num->bnan() if ($mod->{sign} ne '+' # NaN, - , -inf, +inf
+ || $mod->is_zero());
+
+ # check exponent for valid values
+ if ($exp->{sign} =~ /\w/)
+ {
+ # i.e., if it's NaN, +inf, or -inf...
+ return $num->bnan();
+ }
+
+ $num->bmodinv ($mod) if ($exp->{sign} eq '-');
+
+ # check num for valid values (also NaN if there was no inverse but $exp < 0)
+ return $num->bnan() if $num->{sign} !~ /^[+-]$/;
+
+ # $mod is positive, sign on $exp is ignored, result also positive
+
+ # XXX TODO: speed it up when all three numbers are integers
+ $num->bpow($exp)->bmod($mod);
+ }
+
+###############################################################################
+# trigonometric functions
+
+# helper function for bpi() and batan2(), calculates arcus tanges (1/x)
+
+sub _atan_inv
+ {
+ # return a/b so that a/b approximates atan(1/x) to at least limit digits
+ my ($self, $x, $limit) = @_;
+
+ # Taylor: x^3 x^5 x^7 x^9
+ # atan = x - --- + --- - --- + --- - ...
+ # 3 5 7 9
+
+ # 1 1 1 1
+ # atan 1/x = - - ------- + ------- - ------- + ...
+ # x x^3 * 3 x^5 * 5 x^7 * 7
+
+ # 1 1 1 1
+ # atan 1/x = - - --------- + ---------- - ----------- + ...
+ # 5 3 * 125 5 * 3125 7 * 78125
+
+ # Subtraction/addition of a rational:
+
+ # 5 7 5*3 +- 7*4
+ # - +- - = ----------
+ # 4 3 4*3
+
+ # Term: N N+1
+ #
+ # a 1 a * d * c +- b
+ # ----- +- ------------------ = ----------------
+ # b d * c b * d * c
+
+ # since b1 = b0 * (d-2) * c
+
+ # a 1 a * d +- b / c
+ # ----- +- ------------------ = ----------------
+ # b d * c b * d
+
+ # and d = d + 2
+ # and c = c * x * x
+
+ # u = d * c
+ # stop if length($u) > limit
+ # a = a * u +- b
+ # b = b * u
+ # d = d + 2
+ # c = c * x * x
+ # sign = 1 - sign
+
+ my $a = $MBI->_one();
+ my $b = $MBI->_copy($x);
+
+ my $x2 = $MBI->_mul( $MBI->_copy($x), $b); # x2 = x * x
+ my $d = $MBI->_new( 3 ); # d = 3
+ my $c = $MBI->_mul( $MBI->_copy($x), $x2); # c = x ^ 3
+ my $two = $MBI->_new( 2 );
+
+ # run the first step unconditionally
+ my $u = $MBI->_mul( $MBI->_copy($d), $c);
+ $a = $MBI->_mul($a, $u);
+ $a = $MBI->_sub($a, $b);
+ $b = $MBI->_mul($b, $u);
+ $d = $MBI->_add($d, $two);
+ $c = $MBI->_mul($c, $x2);
+
+ # a is now a * (d-3) * c
+ # b is now b * (d-2) * c
+
+ # run the second step unconditionally
+ $u = $MBI->_mul( $MBI->_copy($d), $c);
+ $a = $MBI->_mul($a, $u);
+ $a = $MBI->_add($a, $b);
+ $b = $MBI->_mul($b, $u);
+ $d = $MBI->_add($d, $two);
+ $c = $MBI->_mul($c, $x2);
+
+ # a is now a * (d-3) * (d-5) * c * c
+ # b is now b * (d-2) * (d-4) * c * c
+
+ # so we can remove c * c from both a and b to shorten the numbers involved:
+ $a = $MBI->_div($a, $x2);
+ $b = $MBI->_div($b, $x2);
+ $a = $MBI->_div($a, $x2);
+ $b = $MBI->_div($b, $x2);
+
+# my $step = 0;
+ my $sign = 0; # 0 => -, 1 => +
+ while (3 < 5)
+ {
+# $step++;
+# if (($i++ % 100) == 0)
+# {
+# print "a=",$MBI->_str($a),"\n";
+# print "b=",$MBI->_str($b),"\n";
+# }
+# print "d=",$MBI->_str($d),"\n";
+# print "x2=",$MBI->_str($x2),"\n";
+# print "c=",$MBI->_str($c),"\n";
+
+ my $u = $MBI->_mul( $MBI->_copy($d), $c);
+ # use _alen() for libs like GMP where _len() would be O(N^2)
+ last if $MBI->_alen($u) > $limit;
+ my ($bc,$r) = $MBI->_div( $MBI->_copy($b), $c);
+ if ($MBI->_is_zero($r))
+ {
+ # b / c is an integer, so we can remove c from all terms
+ # this happens almost every time:
+ $a = $MBI->_mul($a, $d);
+ $a = $MBI->_sub($a, $bc) if $sign == 0;
+ $a = $MBI->_add($a, $bc) if $sign == 1;
+ $b = $MBI->_mul($b, $d);
+ }
+ else
+ {
+ # b / c is not an integer, so we keep c in the terms
+ # this happens very rarely, for instance for x = 5, this happens only
+ # at the following steps:
+ # 1, 5, 14, 32, 72, 157, 340, ...
+ $a = $MBI->_mul($a, $u);
+ $a = $MBI->_sub($a, $b) if $sign == 0;
+ $a = $MBI->_add($a, $b) if $sign == 1;
+ $b = $MBI->_mul($b, $u);
+ }
+ $d = $MBI->_add($d, $two);
+ $c = $MBI->_mul($c, $x2);
+ $sign = 1 - $sign;
+
+ }
+
+# print "Took $step steps for ", $MBI->_str($x),"\n";
+# print "a=",$MBI->_str($a),"\n"; print "b=",$MBI->_str($b),"\n";
+ # return a/b so that a/b approximates atan(1/x)
+ ($a,$b);
+ }
+
+sub bpi
+ {
+ my ($self,$n) = @_;
+ if (@_ == 0)
+ {
+ $self = $class;
+ }
+ if (@_ == 1)
+ {
+ # called like Math::BigFloat::bpi(10);
+ $n = $self; $self = $class;
+ # called like Math::BigFloat->bpi();
+ $n = undef if $n eq 'Math::BigFloat';
+ }
+ $self = ref($self) if ref($self);
+ my $fallback = defined $n ? 0 : 1;
+ $n = 40 if !defined $n || $n < 1;
+
+ # after 黃見利 (Hwang Chien-Lih) (1997)
+ # pi/4 = 183 * atan(1/239) + 32 * atan(1/1023) – 68 * atan(1/5832)
+ # + 12 * atan(1/110443) - 12 * atan(1/4841182) - 100 * atan(1/6826318)
+
+ # a few more to prevent rounding errors
+ $n += 4;
+
+ my ($a,$b) = $self->_atan_inv( $MBI->_new(239),$n);
+ my ($c,$d) = $self->_atan_inv( $MBI->_new(1023),$n);
+ my ($e,$f) = $self->_atan_inv( $MBI->_new(5832),$n);
+ my ($g,$h) = $self->_atan_inv( $MBI->_new(110443),$n);
+ my ($i,$j) = $self->_atan_inv( $MBI->_new(4841182),$n);
+ my ($k,$l) = $self->_atan_inv( $MBI->_new(6826318),$n);
+
+ $MBI->_mul($a, $MBI->_new(732));
+ $MBI->_mul($c, $MBI->_new(128));
+ $MBI->_mul($e, $MBI->_new(272));
+ $MBI->_mul($g, $MBI->_new(48));
+ $MBI->_mul($i, $MBI->_new(48));
+ $MBI->_mul($k, $MBI->_new(400));
+
+ my $x = $self->bone(); $x->{_m} = $a; my $x_d = $self->bone(); $x_d->{_m} = $b;
+ my $y = $self->bone(); $y->{_m} = $c; my $y_d = $self->bone(); $y_d->{_m} = $d;
+ my $z = $self->bone(); $z->{_m} = $e; my $z_d = $self->bone(); $z_d->{_m} = $f;
+ my $u = $self->bone(); $u->{_m} = $g; my $u_d = $self->bone(); $u_d->{_m} = $h;
+ my $v = $self->bone(); $v->{_m} = $i; my $v_d = $self->bone(); $v_d->{_m} = $j;
+ my $w = $self->bone(); $w->{_m} = $k; my $w_d = $self->bone(); $w_d->{_m} = $l;
+ $x->bdiv($x_d, $n);
+ $y->bdiv($y_d, $n);
+ $z->bdiv($z_d, $n);
+ $u->bdiv($u_d, $n);
+ $v->bdiv($v_d, $n);
+ $w->bdiv($w_d, $n);
+
+ delete $x->{_a}; delete $y->{_a}; delete $z->{_a};
+ delete $u->{_a}; delete $v->{_a}; delete $w->{_a};
+ $x->badd($y)->bsub($z)->badd($u)->bsub($v)->bsub($w);
+
+ $x->bround($n-4);
+ delete $x->{_a} if $fallback == 1;
+ $x;
+ }
+
+sub bcos
+ {
+ # Calculate a cosinus of x.
+ my ($self,$x,@r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+
+ # Taylor: x^2 x^4 x^6 x^8
+ # cos = 1 - --- + --- - --- + --- ...
+ # 2! 4! 6! 8!
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($x,@params) = $x->_find_round_parameters(@r);
+
+ # constant object or error in _find_round_parameters?
+ return $x if $x->modify('bcos') || $x->is_nan();
+
+ return $x->bone(@r) if $x->is_zero();
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # disable P
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r[2]; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it is not
+ # enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ # when user set globals, they would interfere with our calculation, so
+ # disable them and later re-enable them
+ no strict 'refs';
+ my $abr = "$self\::accuracy"; my $ab = $$abr; $$abr = undef;
+ my $pbr = "$self\::precision"; my $pb = $$pbr; $$pbr = undef;
+ # we also need to disable any set A or P on $x (_find_round_parameters took
+ # them already into account), since these would interfere, too
+ delete $x->{_a}; delete $x->{_p};
+ # need to disable $upgrade in BigInt, to avoid deep recursion
+ local $Math::BigInt::upgrade = undef;
+
+ my $last = 0;
+ my $over = $x * $x; # X ^ 2
+ my $x2 = $over->copy(); # X ^ 2; difference between terms
+ my $sign = 1; # start with -=
+ my $below = $self->new(2); my $factorial = $self->new(3);
+ $x->bone(); delete $x->{_a}; delete $x->{_p};
+
+ my $limit = $self->new("1E-". ($scale-1));
+ #my $steps = 0;
+ while (3 < 5)
+ {
+ # we calculate the next term, and add it to the last
+ # when the next term is below our limit, it won't affect the outcome
+ # anymore, so we stop:
+ my $next = $over->copy()->bdiv($below,$scale);
+ last if $next->bacmp($limit) <= 0;
+
+ if ($sign == 0)
+ {
+ $x->badd($next);
+ }
+ else
+ {
+ $x->bsub($next);
+ }
+ $sign = 1-$sign; # alternate
+ # calculate things for the next term
+ $over->bmul($x2); # $x*$x
+ $below->bmul($factorial); $factorial->binc(); # n*(n+1)
+ $below->bmul($factorial); $factorial->binc(); # n*(n+1)
+ }
+
+ # shortcut to not run through _find_round_parameters again
+ if (defined $params[0])
+ {
+ $x->bround($params[0],$params[2]); # then round accordingly
+ }
+ else
+ {
+ $x->bfround($params[1],$params[2]); # then round accordingly
+ }
+ if ($fallback)
+ {
+ # clear a/p after round, since user did not request it
+ delete $x->{_a}; delete $x->{_p};
+ }
+ # restore globals
+ $$abr = $ab; $$pbr = $pb;
+ $x;
+ }
+
+sub bsin
+ {
+ # Calculate a sinus of x.
+ my ($self,$x,@r) = ref($_[0]) ? (ref($_[0]),@_) : objectify(1,@_);
+
+ # taylor: x^3 x^5 x^7 x^9
+ # sin = x - --- + --- - --- + --- ...
+ # 3! 5! 7! 9!
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($x,@params) = $x->_find_round_parameters(@r);
+
+ # constant object or error in _find_round_parameters?
+ return $x if $x->modify('bsin') || $x->is_nan();
+
+ return $x->bzero(@r) if $x->is_zero();
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # disable P
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r[2]; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it is not
+ # enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ # when user set globals, they would interfere with our calculation, so
+ # disable them and later re-enable them
+ no strict 'refs';
+ my $abr = "$self\::accuracy"; my $ab = $$abr; $$abr = undef;
+ my $pbr = "$self\::precision"; my $pb = $$pbr; $$pbr = undef;
+ # we also need to disable any set A or P on $x (_find_round_parameters took
+ # them already into account), since these would interfere, too
+ delete $x->{_a}; delete $x->{_p};
+ # need to disable $upgrade in BigInt, to avoid deep recursion
+ local $Math::BigInt::upgrade = undef;
+
+ my $last = 0;
+ my $over = $x * $x; # X ^ 2
+ my $x2 = $over->copy(); # X ^ 2; difference between terms
+ $over->bmul($x); # X ^ 3 as starting value
+ my $sign = 1; # start with -=
+ my $below = $self->new(6); my $factorial = $self->new(4);
+ delete $x->{_a}; delete $x->{_p};
+
+ my $limit = $self->new("1E-". ($scale-1));
+ #my $steps = 0;
+ while (3 < 5)
+ {
+ # we calculate the next term, and add it to the last
+ # when the next term is below our limit, it won't affect the outcome
+ # anymore, so we stop:
+ my $next = $over->copy()->bdiv($below,$scale);
+ last if $next->bacmp($limit) <= 0;
+
+ if ($sign == 0)
+ {
+ $x->badd($next);
+ }
+ else
+ {
+ $x->bsub($next);
+ }
+ $sign = 1-$sign; # alternate
+ # calculate things for the next term
+ $over->bmul($x2); # $x*$x
+ $below->bmul($factorial); $factorial->binc(); # n*(n+1)
+ $below->bmul($factorial); $factorial->binc(); # n*(n+1)
+ }
+
+ # shortcut to not run through _find_round_parameters again
+ if (defined $params[0])
+ {
+ $x->bround($params[0],$params[2]); # then round accordingly
+ }
+ else
+ {
+ $x->bfround($params[1],$params[2]); # then round accordingly
+ }
+ if ($fallback)
+ {
+ # clear a/p after round, since user did not request it
+ delete $x->{_a}; delete $x->{_p};
+ }
+ # restore globals
+ $$abr = $ab; $$pbr = $pb;
+ $x;
+ }
+
+sub batan2
+ {
+ # calculate arcus tangens of ($y/$x)
+
+ # set up parameters
+ my ($self,$y,$x,@r) = (ref($_[0]),@_);
+ # objectify is costly, so avoid it
+ if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
+ {
+ ($self,$y,$x,@r) = objectify(2,@_);
+ }
+
+ return $y if $y->modify('batan2');
+
+ return $y->bnan() if ($y->{sign} eq $nan) || ($x->{sign} eq $nan);
+
+ return $upgrade->new($y)->batan2($upgrade->new($x),@r) if defined $upgrade;
+
+ # Y X
+ # 0 0 result is 0
+ # 0 +x result is 0
+ return $y->bzero(@r) if $y->is_zero() && $x->{sign} eq '+';
+
+ # Y X
+ # 0 -x result is PI
+ if ($y->is_zero())
+ {
+ # calculate PI
+ my $pi = $self->bpi(@r);
+ # modify $x in place
+ $y->{_m} = $pi->{_m};
+ $y->{_e} = $pi->{_e};
+ $y->{_es} = $pi->{_es};
+ $y->{sign} = '+';
+ return $y;
+ }
+
+ # Y X
+ # +y 0 result is PI/2
+ # -y 0 result is -PI/2
+ if ($y->is_inf() || $x->is_zero())
+ {
+ # calculate PI/2
+ my $pi = $self->bpi(@r);
+ # modify $x in place
+ $y->{_m} = $pi->{_m};
+ $y->{_e} = $pi->{_e};
+ $y->{_es} = $pi->{_es};
+ # -y => -PI/2, +y => PI/2
+ $y->{sign} = substr($y->{sign},0,1); # +inf => +
+ $MBI->_div($y->{_m}, $MBI->_new(2));
+ return $y;
+ }
+
+ # we need to limit the accuracy to protect against overflow
+ my $fallback = 0;
+ my ($scale,@params);
+ ($y,@params) = $y->_find_round_parameters(@r);
+
+ # error in _find_round_parameters?
+ return $y if $y->is_nan();
+
+ # no rounding at all, so must use fallback
+ if (scalar @params == 0)
+ {
+ # simulate old behaviour
+ $params[0] = $self->div_scale(); # and round to it as accuracy
+ $params[1] = undef; # disable P
+ $scale = $params[0]+4; # at least four more for proper round
+ $params[2] = $r[2]; # round mode by caller or undef
+ $fallback = 1; # to clear a/p afterwards
+ }
+ else
+ {
+ # the 4 below is empirical, and there might be cases where it is not
+ # enough...
+ $scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
+ }
+
+ # inlined is_one() && is_one('-')
+ if ($MBI->_is_one($y->{_m}) && $MBI->_is_zero($y->{_e}))
+ {
+ # shortcut: 1 1 result is PI/4
+ # inlined is_one() && is_one('-')
+ if ($MBI->_is_one($x->{_m}) && $MBI->_is_zero($x->{_e}))
+ {
+ # 1,1 => PI/4
+ my $pi_4 = $self->bpi( $scale - 3);
+ # modify $x in place
+ $y->{_m} = $pi_4->{_m};
+ $y->{_e} = $pi_4->{_e};
+ $y->{_es} = $pi_4->{_es};
+ # 1 1 => +
+ # -1 1 => -
+ # 1 -1 => -
+ # -1 -1 => +
+ $y->{sign} = $x->{sign} eq $y->{sign} ? '+' : '-';
+ $MBI->_div($y->{_m}, $MBI->_new(4));
+ return $y;
+ }
+ # shortcut: 1 int(X) result is _atan_inv(X)
+
+ # is integer
+ if ($x->{_es} eq '+')
+ {
+ my $x1 = $MBI->_copy($x->{_m});
+ $MBI->_lsft($x1, $x->{_e},10) unless $MBI->_is_zero($x->{_e});
+
+ my ($a,$b) = $self->_atan_inv($x1, $scale);
+ my $y_sign = $y->{sign};
+ # calculate A/B
+ $y->bone(); $y->{_m} = $a; my $y_d = $self->bone(); $y_d->{_m} = $b;
+ $y->bdiv($y_d, @r);
+ $y->{sign} = $y_sign;
+ return $y;
+ }
+ }
+
+ # handle all other cases
+ # X Y
+ # +x +y 0 to PI/2
+ # -x +y PI/2 to PI
+ # +x -y 0 to -PI/2
+ # -x -y -PI/2 to -PI
+
+ my $y_sign = $y->{sign};
+
+ # divide $x by $y
+ $y->bdiv($x, $scale) unless $x->is_one();
+ $y->batan(@r);
+
+ # restore sign
+ $y->{sign} = $y_sign;
+
+ $y;
}
-sub _pow
+sub batan
{
- # Calculate a power where $y is a non-integer, like 2 ** 0.5
- my ($x,$y,$a,$p,$r) = @_;
+ # Calculate a arcus tangens of x.
+ my ($x,@r) = @_;
my $self = ref($x);
- # if $y == 0.5, it is sqrt($x)
- $HALF = $self->new($HALF) unless ref($HALF);
- return $x->bsqrt($a,$p,$r,$y) if $y->bcmp($HALF) == 0;
-
- # Using:
- # a ** x == e ** (x * ln a)
-
- # u = y * ln x
- # _ _
- # Taylor: | u u^2 u^3 |
- # x ** y = 1 + | --- + --- + ----- + ... |
- # |_ 1 1*2 1*2*3 _|
+ # taylor: x^3 x^5 x^7 x^9
+ # atan = x - --- + --- - --- + --- ...
+ # 3 5 7 9
# we need to limit the accuracy to protect against overflow
my $fallback = 0;
my ($scale,@params);
- ($x,@params) = $x->_find_round_parameters($a,$p,$r);
+ ($x,@params) = $x->_find_round_parameters(@r);
- return $x if $x->is_nan(); # error in _find_round_parameters?
+ # constant object or error in _find_round_parameters?
+ return $x if $x->modify('batan') || $x->is_nan();
+
+ if ($x->{sign} =~ /^[+-]inf\z/)
+ {
+ # +inf result is PI/2
+ # -inf result is -PI/2
+ # calculate PI/2
+ my $pi = $self->bpi(@r);
+ # modify $x in place
+ $x->{_m} = $pi->{_m};
+ $x->{_e} = $pi->{_e};
+ $x->{_es} = $pi->{_es};
+ # -y => -PI/2, +y => PI/2
+ $x->{sign} = substr($x->{sign},0,1); # +inf => +
+ $MBI->_div($x->{_m}, $MBI->_new(2));
+ return $x;
+ }
+
+ return $x->bzero(@r) if $x->is_zero();
# no rounding at all, so must use fallback
if (scalar @params == 0)
$params[0] = $self->div_scale(); # and round to it as accuracy
$params[1] = undef; # disable P
$scale = $params[0]+4; # at least four more for proper round
- $params[2] = $r; # round mode by caller or undef
+ $params[2] = $r[2]; # round mode by caller or undef
$fallback = 1; # to clear a/p afterwards
}
else
$scale = abs($params[0] || $params[1]) + 4; # take whatever is defined
}
+ # 1 or -1 => PI/4
+ # inlined is_one() && is_one('-')
+ if ($MBI->_is_one($x->{_m}) && $MBI->_is_zero($x->{_e}))
+ {
+ my $pi = $self->bpi($scale - 3);
+ # modify $x in place
+ $x->{_m} = $pi->{_m};
+ $x->{_e} = $pi->{_e};
+ $x->{_es} = $pi->{_es};
+ # leave the sign of $x alone (+1 => +PI/4, -1 => -PI/4)
+ $MBI->_div($x->{_m}, $MBI->_new(4));
+ return $x;
+ }
+
+ # This series is only valid if -1 < x < 1, so for other x we need to
+ # to calculate PI/ - atan(1/x):
+ my $one = $MBI->_new(1);
+ my $pi = undef;
+ if ($x->{_es} eq '+' && ($MBI->_acmp($x->{_m},$one) >= 0))
+ {
+ # calculate PI/2
+ $pi = $self->bpi($scale - 3);
+ $MBI->_div($pi->{_m}, $MBI->_new(2));
+ # calculate 1/$x:
+ my $x_copy = $x->copy();
+ # modify $x in place
+ $x->bone(); $x->bdiv($x_copy,$scale);
+ }
+
# when user set globals, they would interfere with our calculation, so
# disable them and later re-enable them
no strict 'refs';
# need to disable $upgrade in BigInt, to avoid deep recursion
local $Math::BigInt::upgrade = undef;
- my ($limit,$v,$u,$below,$factor,$next,$over);
-
- $u = $x->copy()->blog(undef,$scale)->bmul($y);
- $v = $self->bone(); # 1
- $factor = $self->new(2); # 2
- $x->bone(); # first term: 1
-
- $below = $v->copy();
- $over = $u->copy();
+ my $last = 0;
+ my $over = $x * $x; # X ^ 2
+ my $x2 = $over->copy(); # X ^ 2; difference between terms
+ $over->bmul($x); # X ^ 3 as starting value
+ my $sign = 1; # start with -=
+ my $below = $self->new(3);
+ my $two = $self->new(2);
+ delete $x->{_a}; delete $x->{_p};
- $limit = $self->new("1E-". ($scale-1));
+ my $limit = $self->new("1E-". ($scale-1));
#my $steps = 0;
while (3 < 5)
{
# we calculate the next term, and add it to the last
# when the next term is below our limit, it won't affect the outcome
- # anymore, so we stop
- $next = $over->copy()->bdiv($below,$scale);
+ # anymore, so we stop:
+ my $next = $over->copy()->bdiv($below,$scale);
last if $next->bacmp($limit) <= 0;
- $x->badd($next);
- # calculate things for the next term
- $over *= $u; $below *= $factor; $factor->binc();
- last if $x->{sign} !~ /^[-+]$/;
+ if ($sign == 0)
+ {
+ $x->badd($next);
+ }
+ else
+ {
+ $x->bsub($next);
+ }
+ $sign = 1-$sign; # alternate
+ # calculate things for the next term
+ $over->bmul($x2); # $x*$x
+ $below->badd($two); # n += 2
+ }
- #$steps++;
+ if (defined $pi)
+ {
+ my $x_copy = $x->copy();
+ # modify $x in place
+ $x->{_m} = $pi->{_m};
+ $x->{_e} = $pi->{_e};
+ $x->{_es} = $pi->{_es};
+ # PI/2 - $x
+ $x->bsub($x_copy);
}
-
+
# shortcut to not run through _find_round_parameters again
if (defined $params[0])
{
$x;
}
-sub bpow
- {
- # (BFLOAT or num_str, BFLOAT or num_str) return BFLOAT
- # compute power of two numbers, second arg is used as integer
- # modifies first argument
-
- # set up parameters
- my ($self,$x,$y,$a,$p,$r) = (ref($_[0]),@_);
- # objectify is costly, so avoid it
- if ((!ref($_[0])) || (ref($_[0]) ne ref($_[1])))
- {
- ($self,$x,$y,$a,$p,$r) = objectify(2,@_);
- }
-
- return $x if $x->{sign} =~ /^[+-]inf$/;
- return $x->bnan() if $x->{sign} eq $nan || $y->{sign} eq $nan;
-
- # cache the result of is_zero
- my $y_is_zero = $y->is_zero();
- return $x->bone() if $y_is_zero;
- return $x if $x->is_one() || $y->is_one();
-
- my $x_is_zero = $x->is_zero();
- return $x->_pow($y,$a,$p,$r) if !$x_is_zero && !$y->is_int(); # non-integer power
-
- my $y1 = $y->as_number()->{value}; # make MBI part
-
- # if ($x == -1)
- if ($x->{sign} eq '-' && $MBI->_is_one($x->{_m}) && $MBI->_is_zero($x->{_e}))
- {
- # if $x == -1 and odd/even y => +1/-1 because +-1 ^ (+-1) => +-1
- return $MBI->_is_odd($y1) ? $x : $x->babs(1);
- }
- if ($x_is_zero)
- {
- return $x->bone() if $y_is_zero;
- return $x if $y->{sign} eq '+'; # 0**y => 0 (if not y <= 0)
- # 0 ** -y => 1 / (0 ** y) => 1 / 0! (1 / 0 => +inf)
- return $x->binf();
- }
-
- my $new_sign = '+';
- $new_sign = $MBI->_is_odd($y1) ? '-' : '+' if $x->{sign} ne '+';
-
- # calculate $x->{_m} ** $y and $x->{_e} * $y separately (faster)
- $x->{_m} = $MBI->_pow( $x->{_m}, $y1);
- $x->{_e} = $MBI->_mul ($x->{_e}, $y1);
-
- $x->{sign} = $new_sign;
- $x->bnorm();
- if ($y->{sign} eq '-')
- {
- # modify $x in place!
- my $z = $x->copy(); $x->bone();
- return $x->bdiv($z,$a,$p,$r); # round in one go (might ignore y's A!)
- }
- $x->round($a,$p,$r,$y);
- }
-
###############################################################################
# rounding functions
# expects and returns normalized numbers!
my $x = shift; my $self = ref($x) || $x; $x = $self->new(shift) if !ref($x);
- return $x if $x->modify('bfround');
-
- my ($scale,$mode) = $x->_scale_p($self->precision(),$self->round_mode(),@_);
- return $x if !defined $scale; # no-op
+ my ($scale,$mode) = $x->_scale_p(@_);
+ return $x if !defined $scale || $x->modify('bfround'); # no-op
# never round a 0, +-inf, NaN
if ($x->is_zero())
require Carp; Carp::croak ('bround() needs positive accuracy');
}
- my ($scale,$mode) = $x->_scale_a($self->accuracy(),$self->round_mode(),@_);
- return $x if !defined $scale; # no-op
-
- return $x if $x->modify('bround');
+ my ($scale,$mode) = $x->_scale_a(@_);
+ return $x if !defined $scale || $x->modify('bround'); # no-op
# scale is now either $x->{_a}, $accuracy, or the user parameter
# test whether $x already has lower accuracy, do nothing in this case
# but do round if the accuracy is the same, since a math operation might
# want to round a number with A=5 to 5 digits afterwards again
- return $x if defined $_[0] && defined $x->{_a} && $x->{_a} < $_[0];
+ return $x if defined $x->{_a} && $x->{_a} < $scale;
# scale < 0 makes no sense
+ # scale == 0 => keep all digits
# never round a +-inf, NaN
- return $x if ($scale < 0) || $x->{sign} !~ /^[+-]$/;
+ return $x if ($scale <= 0) || $x->{sign} !~ /^[+-]$/;
- # 1: $scale == 0 => keep all digits
- # 2: never round a 0
- # 3: if we should keep more digits than the mantissa has, do nothing
- if ($scale == 0 || $x->is_zero() || $MBI->_len($x->{_m}) <= $scale)
+ # 1: never round a 0
+ # 2: if we should keep more digits than the mantissa has, do nothing
+ if ($x->is_zero() || $MBI->_len($x->{_m}) <= $scale)
{
$x->{_a} = $scale if !defined $x->{_a} || $x->{_a} > $scale;
return $x;
return $x if $x->{sign} !~ /^[+-]$/; # nan, +inf, -inf
$n = 2 if !defined $n; $n = $self->new($n);
+
+ # negative amount?
+ return $x->blsft($y->copy()->babs(),$n) if $y->{sign} =~ /^-/;
+
+ # the following call to bdiv() will return either quo or (quo,reminder):
$x->bdiv($n->bpow($y),$a,$p,$r,$y);
}
return $x if $x->{sign} !~ /^[+-]$/; # nan, +inf, -inf
$n = 2 if !defined $n; $n = $self->new($n);
+
+ # negative amount?
+ return $x->brsft($y->copy()->babs(),$n) if $y->{sign} =~ /^-/;
+
$x->bmul($n->bpow($y),$a,$p,$r,$y);
}
my $c = $1 || $class;
no strict 'refs';
$c->import() if $IMPORT == 0;
- if (!method_alias($name))
+ if (!_method_alias($name))
{
if (!defined $name)
{
require Carp;
Carp::croak ("$c: Can't call a method without name");
}
- if (!method_hand_up($name))
+ if (!_method_hand_up($name))
{
# delayed load of Carp and avoid recursion
require Carp;
my $self = shift;
my $l = scalar @_;
my $lib = ''; my @a;
+ my $lib_kind = 'try';
$IMPORT=1;
for ( my $i = 0; $i < $l ; $i++)
{
$downgrade = $_[$i+1]; # or undef to disable
$i++;
}
- elsif ($_[$i] eq 'lib')
+ elsif ($_[$i] =~ /^(lib|try|only)\z/)
{
# alternative library
$lib = $_[$i+1] || ''; # default Calc
+ $lib_kind = $1; # lib, try or only
$i++;
}
elsif ($_[$i] eq 'with')
}
}
+ $lib =~ tr/a-zA-Z0-9,://cd; # restrict to sane characters
# let use Math::BigInt lib => 'GMP'; use Math::BigFloat; still work
my $mbilib = eval { Math::BigInt->config()->{lib} };
if ((defined $mbilib) && ($MBI eq 'Math::BigInt::Calc'))
{
# MBI already loaded
- Math::BigInt->import('lib',"$lib,$mbilib", 'objectify');
+ Math::BigInt->import( $lib_kind, "$lib,$mbilib", 'objectify');
}
else
{
# MBI not loaded, or with ne "Math::BigInt::Calc"
$lib .= ",$mbilib" if defined $mbilib;
$lib =~ s/^,//; # don't leave empty
+
# replacement library can handle lib statement, but also could ignore it
- if ($] < 5.006)
- {
- # Perl < 5.6.0 dies with "out of memory!" when eval() and ':constant' is
- # used in the same script, or eval inside import().
- require Math::BigInt;
- Math::BigInt->import( lib => $lib, 'objectify' );
- }
- else
- {
- my $rc = "use Math::BigInt lib => '$lib', 'objectify';";
- eval $rc;
- }
+
+ # Perl < 5.6.0 dies with "out of memory!" when eval() and ':constant' is
+ # used in the same script, or eval inside import(). So we require MBI:
+ require Math::BigInt;
+ Math::BigInt->import( $lib_kind => $lib, 'objectify' );
}
if ($@)
{
require Carp; Carp::croak ("Couldn't load $lib: $! $@");
}
+ # find out which one was actually loaded
$MBI = Math::BigInt->config()->{lib};
- # any non :constant stuff is handled by our parent, Exporter
- # even if @_ is empty, to give it a chance
- $self->SUPER::import(@a); # for subclasses
- $self->export_to_level(1,$self,@a); # need this, too
+ # register us with MBI to get notified of future lib changes
+ Math::BigInt::_register_callback( $self, sub { $MBI = $_[0]; } );
+
+ $self->export_to_level(1,$self,@a); # export wanted functions
}
sub bnorm
{
# adjust m and e so that m is smallest possible
- # round number according to accuracy and precision settings
my ($self,$x) = ref($_[0]) ? (undef,$_[0]) : objectify(1,@_);
return $x if $x->{sign} !~ /^[+-]$/; # inf, nan etc
{
if ($MBI->_acmp($x->{_e},$z) >= 0)
{
- $x->{_e} = $MBI->_sub ($x->{_e}, $z);
+ $x->{_e} = $MBI->_sub ($x->{_e}, $z);
$x->{_es} = '+' if $MBI->_is_zero($x->{_e});
}
else
{
- $x->{_e} = $MBI->_sub ( $MBI->_copy($z), $x->{_e});
+ $x->{_e} = $MBI->_sub ( $MBI->_copy($z), $x->{_e});
$x->{_es} = '+';
}
}
else
{
- $x->{_e} = $MBI->_add ($x->{_e}, $z);
+ $x->{_e} = $MBI->_add ($x->{_e}, $z);
}
}
else
$z->as_bin();
}
+sub as_oct
+ {
+ # return number as octal digit string (only for integers defined)
+ my ($self,$x) = ref($_[0]) ? (ref($_[0]),$_[0]) : objectify(1,@_);
+
+ return $x->bstr() if $x->{sign} !~ /^[+-]$/; # inf, nan etc
+ return '0' if $x->is_zero();
+
+ return $nan if $x->{_es} ne '+'; # how to do 1e-1 in hex!?
+
+ my $z = $MBI->_copy($x->{_m});
+ if (! $MBI->_is_zero($x->{_e})) # > 0
+ {
+ $MBI->_lsft( $z, $x->{_e},10);
+ }
+ $z = Math::BigInt->new( $x->{sign} . $MBI->_num($z));
+ $z->as_oct();
+ }
+
sub as_number
{
# return copy as a bigint representation of this BigFloat number
my ($self,$x) = ref($_[0]) ? (ref($_[0]),$_[0]) : objectify(1,@_);
+ return $x if $x->modify('as_number');
+
my $z = $MBI->_copy($x->{_m});
if ($x->{_es} eq '-') # < 0
{
use Math::BigFloat;
# Number creation
- $x = Math::BigFloat->new($str); # defaults to 0
- $nan = Math::BigFloat->bnan(); # create a NotANumber
- $zero = Math::BigFloat->bzero(); # create a +0
- $inf = Math::BigFloat->binf(); # create a +inf
- $inf = Math::BigFloat->binf('-'); # create a -inf
- $one = Math::BigFloat->bone(); # create a +1
- $one = Math::BigFloat->bone('-'); # create a -1
+ my $x = Math::BigFloat->new($str); # defaults to 0
+ my $y = $x->copy(); # make a true copy
+ my $nan = Math::BigFloat->bnan(); # create a NotANumber
+ my $zero = Math::BigFloat->bzero(); # create a +0
+ my $inf = Math::BigFloat->binf(); # create a +inf
+ my $inf = Math::BigFloat->binf('-'); # create a -inf
+ my $one = Math::BigFloat->bone(); # create a +1
+ my $mone = Math::BigFloat->bone('-'); # create a -1
+
+ my $pi = Math::BigFloat->bpi(100); # PI to 100 digits
+
+ # the following examples compute their result to 100 digits accuracy:
+ my $cos = Math::BigFloat->new(1)->bcos(100); # cosinus(1)
+ my $sin = Math::BigFloat->new(1)->bsin(100); # sinus(1)
+ my $atan = Math::BigFloat->new(1)->batan(100); # arcus tangens(1)
+
+ my $atan2 = Math::BigFloat->new( 1 )->batan2( 1 ,100); # batan(1)
+ my $atan2 = Math::BigFloat->new( 1 )->batan2( 8 ,100); # batan(1/8)
+ my $atan2 = Math::BigFloat->new( -2 )->batan2( 1 ,100); # batan(-2)
# Testing
$x->is_zero(); # true if arg is +0
# The following all modify their first argument. If you want to preserve
# $x, use $z = $x->copy()->bXXX($y); See under L<CAVEATS> for why this is
- # neccessary when mixing $a = $b assigments with non-overloaded math.
+ # necessary when mixing $a = $b assignments with non-overloaded math.
# set
$x->bzero(); # set $i to 0
$x->bmod($y); # modulus ($x % $y)
$x->bpow($y); # power of arguments ($x ** $y)
- $x->blsft($y); # left shift
- $x->brsft($y); # right shift
- # return (quo,rem) or quo if scalar
+ $x->bmodpow($exp,$mod); # modular exponentation (($num**$exp) % $mod))
+ $x->blsft($y, $n); # left shift by $y places in base $n
+ $x->brsft($y, $n); # right shift by $y places in base $n
+ # returns (quo,rem) or quo if in scalar context
$x->blog(); # logarithm of $x to base e (Euler's number)
$x->blog($base); # logarithm of $x to base $base (f.i. 2)
+ $x->bexp(); # calculate e ** $x where e is Euler's number
$x->band($y); # bit-wise and
$x->bior($y); # bit-wise inclusive or
=head1 DESCRIPTION
-All operators (inlcuding basic math operations) are overloaded if you
+All operators (including basic math operations) are overloaded if you
declare your big floating point numbers as
$i = new Math::BigFloat '12_3.456_789_123_456_789E-2';
=back
-all with optional leading and trailing zeros and/or spaces. Additonally,
+all with optional leading and trailing zeros and/or spaces. Additionally,
numbers are allowed to have an underscore between any two digits.
Empty strings as well as other illegal numbers results in 'NaN'.
See also: L<Rounding|Rounding>.
-Math::BigFloat supports both precision and accuracy. For a full documentation,
-examples and tips on these topics please see the large section in
-L<Math::BigInt>.
+Math::BigFloat supports both precision (rounding to a certain place before or
+after the dot) and accuracy (rounding to a certain number of digits). For a
+full documentation, examples and tips on these topics please see the large
+section about rounding in L<Math::BigInt>.
-Since things like sqrt(2) or 1/3 must presented with a limited precision lest
-a operation consumes all resources, each operation produces no more than
-the requested number of digits.
+Since things like C<sqrt(2)> or C<1 / 3> must presented with a limited
+accuracy lest a operation consumes all resources, each operation produces
+no more than the requested number of digits.
-Please refer to BigInt's documentation for the precedence rules of which
-accuracy/precision setting will be used.
-
-If there is no gloabl precision set, B<and> the operation inquestion was not
-called with a requested precision or accuracy, B<and> the input $x has no
-accuracy or precision set, then a fallback parameter will be used. For
-historical reasons, it is called C<div_scale> and can be accessed via:
+If there is no gloabl precision or accuracy set, B<and> the operation in
+question was not called with a requested precision or accuracy, B<and> the
+input $x has no accuracy or precision set, then a fallback parameter will
+be used. For historical reasons, it is called C<div_scale> and can be accessed
+via:
$d = Math::BigFloat->div_scale(); # query
Math::BigFloat->div_scale($n); # set to $n digits
-The default value is 40 digits.
+The default value for C<div_scale> is 40.
-In case the result of one operation has more precision than specified,
+In case the result of one operation has more digits than specified,
it is rounded. The rounding mode taken is either the default mode, or the one
supplied to the operation after the I<scale>:
$x = Math::BigFloat->new(2);
- Math::BigFloat->precision(5); # 5 digits max
- $y = $x->copy()->bdiv(3); # will give 0.66666
- $y = $x->copy()->bdiv(3,6); # will give 0.666666
- $y = $x->copy()->bdiv(3,6,'odd'); # will give 0.666667
+ Math::BigFloat->accuracy(5); # 5 digits max
+ $y = $x->copy()->bdiv(3); # will give 0.66667
+ $y = $x->copy()->bdiv(3,6); # will give 0.666667
+ $y = $x->copy()->bdiv(3,6,undef,'odd'); # will give 0.666667
Math::BigFloat->round_mode('zero');
- $y = $x->copy()->bdiv(3,6); # will give 0.666666
+ $y = $x->copy()->bdiv(3,6); # will also give 0.666667
+
+Note that C<< Math::BigFloat->accuracy() >> and C<< Math::BigFloat->precision() >>
+set the global variables, and thus B<any> newly created number will be subject
+to the global rounding B<immediately>. This means that in the examples above, the
+C<3> as argument to C<bdiv()> will also get an accuracy of B<5>.
+
+It is less confusing to either calculate the result fully, and afterwards
+round it explicitly, or use the additional parameters to the math
+functions like so:
+
+ use Math::BigFloat;
+ $x = Math::BigFloat->new(2);
+ $y = $x->copy()->bdiv(3);
+ print $y->bround(5),"\n"; # will give 0.66667
+
+ or
+
+ use Math::BigFloat;
+ $x = Math::BigFloat->new(2);
+ $y = $x->copy()->bdiv(3,5); # will give 0.66667
+ print "$y\n";
=head2 Rounding
=back
All rounding functions take as a second parameter a rounding mode from one of
-the following: 'even', 'odd', '+inf', '-inf', 'zero' or 'trunc'.
+the following: 'even', 'odd', '+inf', '-inf', 'zero', 'trunc' or 'common'.
The default rounding mode is 'even'. By using
C<< Math::BigFloat->round_mode($round_mode); >> you can get and set the default
$x = Math::BigFloat->new(2.5);
$y = $x->as_number('odd'); # $y = 3
-=head1 EXAMPLES
-
- # not ready yet
+=head1 METHODS
+
+Math::BigFloat supports all methods that Math::BigInt supports, except it
+calculates non-integer results when possible. Please see L<Math::BigInt>
+for a full description of each method. Below are just the most important
+differences:
+
+=head2 accuracy
+
+ $x->accuracy(5); # local for $x
+ CLASS->accuracy(5); # global for all members of CLASS
+ # Note: This also applies to new()!
+
+ $A = $x->accuracy(); # read out accuracy that affects $x
+ $A = CLASS->accuracy(); # read out global accuracy
+
+Set or get the global or local accuracy, aka how many significant digits the
+results have. If you set a global accuracy, then this also applies to new()!
+
+Warning! The accuracy I<sticks>, e.g. once you created a number under the
+influence of C<< CLASS->accuracy($A) >>, all results from math operations with
+that number will also be rounded.
+
+In most cases, you should probably round the results explicitly using one of
+L<round()>, L<bround()> or L<bfround()> or by passing the desired accuracy
+to the math operation as additional parameter:
+
+ my $x = Math::BigInt->new(30000);
+ my $y = Math::BigInt->new(7);
+ print scalar $x->copy()->bdiv($y, 2); # print 4300
+ print scalar $x->copy()->bdiv($y)->bround(2); # print 4300
+
+=head2 precision()
+
+ $x->precision(-2); # local for $x, round at the second digit right of the dot
+ $x->precision(2); # ditto, round at the second digit left of the dot
+
+ CLASS->precision(5); # Global for all members of CLASS
+ # This also applies to new()!
+ CLASS->precision(-5); # ditto
+
+ $P = CLASS->precision(); # read out global precision
+ $P = $x->precision(); # read out precision that affects $x
+
+Note: You probably want to use L<accuracy()> instead. With L<accuracy> you
+set the number of digits each result should have, with L<precision> you
+set the place where to round!
+
+=head2 bexp()
+
+ $x->bexp($accuracy); # calculate e ** X
+
+Calculates the expression C<e ** $x> where C<e> is Euler's number.
+
+This method was added in v1.82 of Math::BigInt (April 2007).
+
+=head2 bnok()
+
+ $x->bnok($y); # x over y (binomial coefficient n over k)
+
+Calculates the binomial coefficient n over k, also called the "choose"
+function. The result is equivalent to:
+
+ ( n ) n!
+ | - | = -------
+ ( k ) k!(n-k)!
+
+This method was added in v1.84 of Math::BigInt (April 2007).
+
+=head2 bpi()
+
+ print Math::BigFloat->bpi(100), "\n";
+
+Calculate PI to N digits (including the 3 before the dot). The result is
+rounded according to the current rounding mode, which defaults to "even".
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
+=head2 bcos()
+
+ my $x = Math::BigFloat->new(1);
+ print $x->bcos(100), "\n";
+
+Calculate the cosinus of $x, modifying $x in place.
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
+=head2 bsin()
+
+ my $x = Math::BigFloat->new(1);
+ print $x->bsin(100), "\n";
+
+Calculate the sinus of $x, modifying $x in place.
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
+=head2 batan2()
+
+ my $y = Math::BigFloat->new(2);
+ my $x = Math::BigFloat->new(3);
+ print $y->batan2($x), "\n";
+
+Calculate the arcus tanges of C<$y> divided by C<$x>, modifying $y in place.
+See also L<batan()>.
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
+=head2 batan()
+
+ my $x = Math::BigFloat->new(1);
+ print $x->batan(100), "\n";
+
+Calculate the arcus tanges of $x, modifying $x in place. See also L<batan2()>.
+
+This method was added in v1.87 of Math::BigInt (June 2007).
+
+=head2 bmuladd()
+
+ $x->bmuladd($y,$z);
+
+Multiply $x by $y, and then add $z to the result.
+
+This method was added in v1.87 of Math::BigInt (June 2007).
=head1 Autocreating constants
You can change this by using:
- use Math::BigFloat lib => 'BitVect';
+ use Math::BigFloat lib => 'GMP';
+
+Note: The keyword 'lib' will warn when the requested library could not be
+loaded. To suppress the warning use 'try' instead:
+
+ use Math::BigFloat try => 'GMP';
+
+To turn the warning into a die(), use 'only' instead:
+
+ use Math::BigFloat only => 'GMP';
The following would first try to find Math::BigInt::Foo, then
Math::BigInt::Bar, and when this also fails, revert to Math::BigInt::Calc:
use Math::BigFloat lib => 'Foo,Math::BigInt::Bar';
-Calc.pm uses as internal format an array of elements of some decimal base
-(usually 1e7, but this might be differen for some systems) with the least
-significant digit first, while BitVect.pm uses a bit vector of base 2, most
-significant bit first. Other modules might use even different means of
-representing the numbers. See the respective module documentation for further
-details.
+See the respective low-level library documentation for further details.
Please note that Math::BigFloat does B<not> use the denoted library itself,
but it merely passes the lib argument to Math::BigInt. So, instead of the need
require Math::BigFloat;
-This will load the neccessary things (like BigInt) when they are needed, and
+This will load the necessary things (like BigInt) when they are needed, and
automatically.
-Use the lib, Luke! And see L<Using Math::BigInt::Lite> for more details than
-you ever wanted to know about loading a different library.
+See L<Math::BigInt> for more details than you ever wanted to know about using
+a different low-level library.
=head2 Using Math::BigInt::Lite
-It is possible to use L<Math::BigInt::Lite> with Math::BigFloat:
-
- # 1
- use Math::BigFloat with => 'Math::BigInt::Lite';
-
-There is no need to "use Math::BigInt" or "use Math::BigInt::Lite", but you
-can combine these if you want. For instance, you may want to use
-Math::BigInt objects in your main script, too.
+For backwards compatibility reasons it is still possible to
+request a different storage class for use with Math::BigFloat:
- # 2
- use Math::BigInt;
use Math::BigFloat with => 'Math::BigInt::Lite';
-Of course, you can combine this with the C<lib> parameter.
-
- # 3
- use Math::BigFloat with => 'Math::BigInt::Lite', lib => 'GMP,Pari';
-
-There is no need for a "use Math::BigInt;" statement, even if you want to
-use Math::BigInt's, since Math::BigFloat will needs Math::BigInt and thus
-always loads it. But if you add it, add it B<before>:
-
- # 4
- use Math::BigInt;
- use Math::BigFloat with => 'Math::BigInt::Lite', lib => 'GMP,Pari';
-
-Notice that the module with the last C<lib> will "win" and thus
-it's lib will be used if the lib is available:
-
- # 5
- use Math::BigInt lib => 'Bar,Baz';
- use Math::BigFloat with => 'Math::BigInt::Lite', lib => 'Foo';
-
-That would try to load Foo, Bar, Baz and Calc (in that order). Or in other
-words, Math::BigFloat will try to retain previously loaded libs when you
-don't specify it onem but if you specify one, it will try to load them.
-
-Actually, the lib loading order would be "Bar,Baz,Calc", and then
-"Foo,Bar,Baz,Calc", but independend of which lib exists, the result is the
-same as trying the latter load alone, except for the fact that one of Bar or
-Baz might be loaded needlessly in an intermidiate step (and thus hang around
-and waste memory). If neither Bar nor Baz exist (or don't work/compile), they
-will still be tried to be loaded, but this is not as time/memory consuming as
-actually loading one of them. Still, this type of usage is not recommended due
-to these issues.
-
-The old way (loading the lib only in BigInt) still works though:
-
- # 6
- use Math::BigInt lib => 'Bar,Baz';
- use Math::BigFloat;
-
-You can even load Math::BigInt afterwards:
-
- # 7
- use Math::BigFloat;
- use Math::BigInt lib => 'Bar,Baz';
+However, this request is ignored, as the current code now uses the low-level
+math libary for directly storing the number parts.
-But this has the same problems like #5, it will first load Calc
-(Math::BigFloat needs Math::BigInt and thus loads it) and then later Bar or
-Baz, depending on which of them works and is usable/loadable. Since this
-loads Calc unnecc., it is not recommended.
+=head1 EXPORTS
-Since it also possible to just require Math::BigFloat, this poses the question
-about what libary this will use:
+C<Math::BigFloat> exports nothing by default, but can export the C<bpi()> method:
- require Math::BigFloat;
- my $x = Math::BigFloat->new(123); $x += 123;
+ use Math::BigFloat qw/bpi/;
-It will use Calc. Please note that the call to import() is still done, but
-only when you use for the first time some Math::BigFloat math (it is triggered
-via any constructor, so the first time you create a Math::BigFloat, the load
-will happen in the background). This means:
+ print bpi(10), "\n";
- require Math::BigFloat;
- Math::BigFloat->import ( lib => 'Foo,Bar' );
+=head1 BUGS
-would be the same as:
+Please see the file BUGS in the CPAN distribution Math::BigInt for known bugs.
- use Math::BigFloat lib => 'Foo, Bar';
+=head1 CAVEATS
-But don't try to be clever to insert some operations in between:
+Do not try to be clever to insert some operations in between switching
+libraries:
require Math::BigFloat;
- my $x = Math::BigFloat->bone() + 4; # load BigInt and Calc
+ my $matter = Math::BigFloat->bone() + 4; # load BigInt and Calc
Math::BigFloat->import( lib => 'Pari' ); # load Pari, too
- $x = Math::BigFloat->bone()+4; # now use Pari
-
-While this works, it loads Calc needlessly. But maybe you just wanted that?
-
-B<Examples #3 is highly recommended> for daily usage.
-
-=head1 BUGS
+ my $anti_matter = Math::BigFloat->bone()+4; # now use Pari
-Please see the file BUGS in the CPAN distribution Math::BigInt for known bugs.
+This will create objects with numbers stored in two different backend libraries,
+and B<VERY BAD THINGS> will happen when you use these together:
-=head1 CAVEATS
+ my $flash_and_bang = $matter + $anti_matter; # Don't do this!
=over 1
=item bdiv
-The following will probably not do what you expect:
+The following will probably not print what you expect:
print $c->bdiv(123.456),"\n";
It prints both quotient and reminder since print works in list context. Also,
-bdiv() will modify $c, so be carefull. You probably want to use
+bdiv() will modify $c, so be careful. You probably want to use
print $c / 123.456,"\n";
print scalar $c->bdiv(123.456),"\n"; # or if you want to modify $c
instead.
+=item brsft
+
+The following will probably not print what you expect:
+
+ my $c = Math::BigFloat->new('3.14159');
+ print $c->brsft(3,10),"\n"; # prints 0.00314153.1415
+
+It prints both quotient and remainder, since print calls C<brsft()> in list
+context. Also, C<< $c->brsft() >> will modify $c, so be careful.
+You probably want to use
+
+ print scalar $c->copy()->brsft(3,10),"\n";
+ # or if you really want to modify $c
+ print scalar $c->brsft(3,10),"\n";
+
+instead.
+
=item Modifying and =
Beware of:
print $x->bpow($i),"\n"; # ditto
print $x ** $i,"\n"; # leave $x alone
+=item precision() vs. accuracy()
+
+A common pitfall is to use L<precision()> when you want to round a result to
+a certain number of digits:
+
+ use Math::BigFloat;
+
+ Math::BigFloat->precision(4); # does not do what you think it does
+ my $x = Math::BigFloat->new(12345); # rounds $x to "12000"!
+ print "$x\n"; # print "12000"
+ my $y = Math::BigFloat->new(3); # rounds $y to "0"!
+ print "$y\n"; # print "0"
+ $z = $x / $y; # 12000 / 0 => NaN!
+ print "$z\n";
+ print $z->precision(),"\n"; # 4
+
+Replacing L<precision> with L<accuracy> is probably not what you want, either:
+
+ use Math::BigFloat;
+
+ Math::BigFloat->accuracy(4); # enables global rounding:
+ my $x = Math::BigFloat->new(123456); # rounded immediately to "12350"
+ print "$x\n"; # print "123500"
+ my $y = Math::BigFloat->new(3); # rounded to "3
+ print "$y\n"; # print "3"
+ print $z = $x->copy()->bdiv($y),"\n"; # 41170
+ print $z->accuracy(),"\n"; # 4
+
+What you want to use instead is:
+
+ use Math::BigFloat;
+
+ my $x = Math::BigFloat->new(123456); # no rounding
+ print "$x\n"; # print "123456"
+ my $y = Math::BigFloat->new(3); # no rounding
+ print "$y\n"; # print "3"
+ print $z = $x->copy()->bdiv($y,4),"\n"; # 41150
+ print $z->accuracy(),"\n"; # undef
+
+In addition to computing what you expected, the last example also does B<not>
+"taint" the result with an accuracy or precision setting, which would
+influence any further operation.
+
=back
=head1 SEE ALSO
The pragmas L<bignum>, L<bigint> and L<bigrat> might also be of interest
because they solve the autoupgrading/downgrading issue, at least partly.
-The package at
-L<http://search.cpan.org/search?mode=module&query=Math%3A%3ABigInt> contains
+The package at L<http://search.cpan.org/~tels/Math-BigInt> contains
more documentation including a full version history, testcases, empty
subclass files and benchmarks.
=head1 AUTHORS
Mark Biggar, overloaded interface by Ilya Zakharevich.
-Completely rewritten by Tels http://bloodgate.com in 2001, 2002, and still
-at it in 2003.
+Completely rewritten by Tels L<http://bloodgate.com> in 2001 - 2006, and still
+at it in 2007.
=cut
https://perl5.git.perl.org / perl5.git / blobdiff