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Make pp_reverse fetch the lexical $_ from the correct pad
[perl5.git] / lib / bigint.pl
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5303340c 1package bigint;
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2#
3# This library is no longer being maintained, and is included for backward
4# compatibility with Perl 4 programs which may require it.
5#
6# In particular, this should not be used as an example of modern Perl
7# programming techniques.
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8# This legacy library is deprecated and will be removed in a future
9# release of perl.
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10#
11# Suggested alternative: Math::BigInt
b6dbc3e0 12
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13# arbitrary size integer math package
14#
15# by Mark Biggar
16#
17# Canonical Big integer value are strings of the form
18# /^[+-]\d+$/ with leading zeros suppressed
19# Input values to these routines may be strings of the form
20# /^\s*[+-]?[\d\s]+$/.
21# Examples:
22# '+0' canonical zero value
23# ' -123 123 123' canonical value '-123123123'
24# '1 23 456 7890' canonical value '+1234567890'
d1be9408 25# Output values always in canonical form
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26#
27# Actual math is done in an internal format consisting of an array
28# whose first element is the sign (/^[+-]$/) and whose remaining
29# elements are base 100000 digits with the least significant digit first.
30# The string 'NaN' is used to represent the result when input arguments
31# are not numbers, as well as the result of dividing by zero
32#
33# routines provided are:
34#
35# bneg(BINT) return BINT negation
36# babs(BINT) return BINT absolute value
37# bcmp(BINT,BINT) return CODE compare numbers (undef,<0,=0,>0)
38# badd(BINT,BINT) return BINT addition
39# bsub(BINT,BINT) return BINT subtraction
40# bmul(BINT,BINT) return BINT multiplication
41# bdiv(BINT,BINT) return (BINT,BINT) division (quo,rem) just quo if scalar
42# bmod(BINT,BINT) return BINT modulus
43# bgcd(BINT,BINT) return BINT greatest common divisor
44# bnorm(BINT) return BINT normalization
45#
8990e307 46
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47# overcome a floating point problem on certain osnames (posix-bc, os390)
48BEGIN {
49 my $x = 100000.0;
50 my $use_mult = int($x*1e-5)*1e5 == $x ? 1 : 0;
51}
52
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53$zero = 0;
54
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55\f
56# normalize string form of number. Strip leading zeros. Strip any
57# white space and add a sign, if missing.
58# Strings that are not numbers result the value 'NaN'.
8990e307 59
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60sub main'bnorm { #(num_str) return num_str
61 local($_) = @_;
62 s/\s+//g; # strip white space
63 if (s/^([+-]?)0*(\d+)$/$1$2/) { # test if number
859172fe 64 substr($_,0,0) = '+' unless $1; # Add missing sign
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65 s/^-0/+0/;
66 $_;
67 } else {
68 'NaN';
69 }
70}
71
72# Convert a number from string format to internal base 100000 format.
73# Assumes normalized value as input.
74sub internal { #(num_str) return int_num_array
75 local($d) = @_;
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76 ($is,$il) = (substr($d,0,1),length($d)-2);
77 substr($d,0,1) = '';
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78 ($is, reverse(unpack("a" . ($il%5+1) . ("a5" x ($il/5)), $d)));
79}
80
81# Convert a number from internal base 100000 format to string format.
82# This routine scribbles all over input array.
83sub external { #(int_num_array) return num_str
84 $es = shift;
85 grep($_ > 9999 || ($_ = substr('0000'.$_,-5)), @_); # zero pad
86 &'bnorm(join('', $es, reverse(@_))); # reverse concat and normalize
87}
88
89# Negate input value.
90sub main'bneg { #(num_str) return num_str
91 local($_) = &'bnorm(@_);
92 vec($_,0,8) ^= ord('+') ^ ord('-') unless $_ eq '+0';
9d116dd7 93 s/^./N/ unless /^[-+]/; # works both in ASCII and EBCDIC
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94 $_;
95}
96
97# Returns the absolute value of the input.
98sub main'babs { #(num_str) return num_str
99 &abs(&'bnorm(@_));
100}
101
102sub abs { # post-normalized abs for internal use
103 local($_) = @_;
104 s/^-/+/;
105 $_;
106}
107\f
108# Compares 2 values. Returns one of undef, <0, =0, >0. (suitable for sort)
109sub main'bcmp { #(num_str, num_str) return cond_code
859172fe 110 local($x,$y) = (&'bnorm($_[0]),&'bnorm($_[1]));
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111 if ($x eq 'NaN') {
112 undef;
113 } elsif ($y eq 'NaN') {
114 undef;
115 } else {
116 &cmp($x,$y);
117 }
118}
119
120sub cmp { # post-normalized compare for internal use
121 local($cx, $cy) = @_;
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122 return 0 if ($cx eq $cy);
123
124 local($sx, $sy) = (substr($cx, 0, 1), substr($cy, 0, 1));
125 local($ld);
126
127 if ($sx eq '+') {
128 return 1 if ($sy eq '-' || $cy eq '+0');
129 $ld = length($cx) - length($cy);
130 return $ld if ($ld);
131 return $cx cmp $cy;
132 } else { # $sx eq '-'
133 return -1 if ($sy eq '+');
134 $ld = length($cy) - length($cx);
135 return $ld if ($ld);
136 return $cy cmp $cx;
137 }
138
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139}
140
141sub main'badd { #(num_str, num_str) return num_str
859172fe 142 local(*x, *y); ($x, $y) = (&'bnorm($_[0]),&'bnorm($_[1]));
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143 if ($x eq 'NaN') {
144 'NaN';
145 } elsif ($y eq 'NaN') {
146 'NaN';
147 } else {
148 @x = &internal($x); # convert to internal form
149 @y = &internal($y);
150 local($sx, $sy) = (shift @x, shift @y); # get signs
151 if ($sx eq $sy) {
152 &external($sx, &add(*x, *y)); # if same sign add
153 } else {
154 ($x, $y) = (&abs($x),&abs($y)); # make abs
155 if (&cmp($y,$x) > 0) {
156 &external($sy, &sub(*y, *x));
157 } else {
158 &external($sx, &sub(*x, *y));
159 }
160 }
161 }
162}
163
164sub main'bsub { #(num_str, num_str) return num_str
859172fe 165 &'badd($_[0],&'bneg($_[1]));
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166}
167
168# GCD -- Euclids algorithm Knuth Vol 2 pg 296
169sub main'bgcd { #(num_str, num_str) return num_str
859172fe 170 local($x,$y) = (&'bnorm($_[0]),&'bnorm($_[1]));
68decaef 171 if ($x eq 'NaN' || $y eq 'NaN') {
5303340c 172 'NaN';
68decaef 173 } else {
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174 ($x, $y) = ($y,&'bmod($x,$y)) while $y ne '+0';
175 $x;
176 }
177}
178\f
68decaef 179# routine to add two base 1e5 numbers
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180# stolen from Knuth Vol 2 Algorithm A pg 231
181# there are separate routines to add and sub as per Kunth pg 233
182sub add { #(int_num_array, int_num_array) return int_num_array
183 local(*x, *y) = @_;
184 $car = 0;
185 for $x (@x) {
186 last unless @y || $car;
55497cff 187 $x -= 1e5 if $car = (($x += shift(@y) + $car) >= 1e5) ? 1 : 0;
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188 }
189 for $y (@y) {
190 last unless $car;
55497cff 191 $y -= 1e5 if $car = (($y += $car) >= 1e5) ? 1 : 0;
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192 }
193 (@x, @y, $car);
194}
195
68decaef 196# subtract base 1e5 numbers -- stolen from Knuth Vol 2 pg 232, $x > $y
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197sub sub { #(int_num_array, int_num_array) return int_num_array
198 local(*sx, *sy) = @_;
199 $bar = 0;
200 for $sx (@sx) {
201 last unless @y || $bar;
e334a159 202 $sx += 1e5 if $bar = (($sx -= shift(@sy) + $bar) < 0);
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203 }
204 @sx;
205}
206
207# multiply two numbers -- stolen from Knuth Vol 2 pg 233
208sub main'bmul { #(num_str, num_str) return num_str
859172fe 209 local(*x, *y); ($x, $y) = (&'bnorm($_[0]), &'bnorm($_[1]));
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210 if ($x eq 'NaN') {
211 'NaN';
212 } elsif ($y eq 'NaN') {
213 'NaN';
214 } else {
215 @x = &internal($x);
216 @y = &internal($y);
217 local($signr) = (shift @x ne shift @y) ? '-' : '+';
218 @prod = ();
219 for $x (@x) {
859172fe 220 ($car, $cty) = (0, 0);
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221 for $y (@y) {
222 $prod = $x * $y + $prod[$cty] + $car;
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223 if ($use_mult) {
224 $prod[$cty++] =
225 $prod - ($car = int($prod * 1e-5)) * 1e5;
226 }
227 else {
228 $prod[$cty++] =
229 $prod - ($car = int($prod / 1e5)) * 1e5;
230 }
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231 }
232 $prod[$cty] += $car if $car;
233 $x = shift @prod;
234 }
235 &external($signr, @x, @prod);
236 }
237}
238
239# modulus
240sub main'bmod { #(num_str, num_str) return num_str
859172fe 241 (&'bdiv(@_))[1];
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242}
243\f
244sub main'bdiv { #(dividend: num_str, divisor: num_str) return num_str
859172fe 245 local (*x, *y); ($x, $y) = (&'bnorm($_[0]), &'bnorm($_[1]));
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246 return wantarray ? ('NaN','NaN') : 'NaN'
247 if ($x eq 'NaN' || $y eq 'NaN' || $y eq '+0');
248 return wantarray ? ('+0',$x) : '+0' if (&cmp(&abs($x),&abs($y)) < 0);
249 @x = &internal($x); @y = &internal($y);
859172fe 250 $srem = $y[0];
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251 $sr = (shift @x ne shift @y) ? '-' : '+';
252 $car = $bar = $prd = 0;
68decaef 253 if (($dd = int(1e5/($y[$#y]+1))) != 1) {
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254 for $x (@x) {
255 $x = $x * $dd + $car;
1f45ae4a 256 if ($use_mult) {
68decaef 257 $x -= ($car = int($x * 1e-5)) * 1e5;
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258 }
259 else {
260 $x -= ($car = int($x / 1e5)) * 1e5;
261 }
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262 }
263 push(@x, $car); $car = 0;
264 for $y (@y) {
265 $y = $y * $dd + $car;
1f45ae4a 266 if ($use_mult) {
68decaef 267 $y -= ($car = int($y * 1e-5)) * 1e5;
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268 }
269 else {
270 $y -= ($car = int($y / 1e5)) * 1e5;
271 }
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272 }
273 }
274 else {
275 push(@x, 0);
276 }
ed6116ce 277 @q = (); ($v2,$v1) = @y[-2,-1];
5303340c 278 while ($#x > $#y) {
ed6116ce 279 ($u2,$u1,$u0) = @x[-3..-1];
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280 $q = (($u0 == $v1) ? 99999 : int(($u0*1e5+$u1)/$v1));
281 --$q while ($v2*$q > ($u0*1e5+$u1-$q*$v1)*1e5+$u2);
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282 if ($q) {
283 ($car, $bar) = (0,0);
859172fe 284 for ($y = 0, $x = $#x-$#y-1; $y <= $#y; ++$y,++$x) {
5303340c 285 $prd = $q * $y[$y] + $car;
1f45ae4a 286 if ($use_mult) {
68decaef 287 $prd -= ($car = int($prd * 1e-5)) * 1e5;
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288 }
289 else {
290 $prd -= ($car = int($prd / 1e5)) * 1e5;
291 }
68decaef 292 $x[$x] += 1e5 if ($bar = (($x[$x] -= $prd + $bar) < 0));
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293 }
294 if ($x[$#x] < $car + $bar) {
295 $car = 0; --$q;
859172fe 296 for ($y = 0, $x = $#x-$#y-1; $y <= $#y; ++$y,++$x) {
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297 $x[$x] -= 1e5
298 if ($car = (($x[$x] += $y[$y] + $car) > 1e5));
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299 }
300 }
301 }
302 pop(@x); unshift(@q, $q);
303 }
304 if (wantarray) {
305 @d = ();
306 if ($dd != 1) {
307 $car = 0;
308 for $x (reverse @x) {
68decaef 309 $prd = $car * 1e5 + $x;
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310 $car = $prd - ($tmp = int($prd / $dd)) * $dd;
311 unshift(@d, $tmp);
312 }
313 }
314 else {
315 @d = @x;
316 }
8990e307 317 (&external($sr, @q), &external($srem, @d, $zero));
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318 } else {
319 &external($sr, @q);
320 }
321}
3221;