lib/perl5/5.8.8/bigint.pm

   1 package bigint;
   2 require 5.005;
   3
   4 $VERSION = '0.07';
   5 use Exporter;
   6 @ISA            = qw( Exporter );
   7 @EXPORT_OK      = qw( );
   8 @EXPORT         = qw( inf NaN );
   9
  10 use strict;
  11 use overload;
  12
  13 ##############################################################################
  14
  15 # These are all alike, and thus faked by AUTOLOAD
  16
  17 my @faked = qw/round_mode accuracy precision div_scale/;
  18 use vars qw/$VERSION $AUTOLOAD $_lite/;         # _lite for testsuite
  19
  20 sub AUTOLOAD
  21   {
  22   my $name = $AUTOLOAD;
  23
  24   $name =~ s/.*:://;    # split package
  25   no strict 'refs';
  26   foreach my $n (@faked)
  27     {
  28     if ($n eq $name)
  29       {
  30       *{"bigint::$name"} = sub
  31         {
  32         my $self = shift;
  33         no strict 'refs';
  34         if (defined $_[0])
  35           {
  36           return Math::BigInt->$name($_[0]);
  37           }
  38         return Math::BigInt->$name();
  39         };
  40       return &$name;
  41       }
  42     }
  43
  44   # delayed load of Carp and avoid recursion
  45   require Carp;
  46   Carp::croak ("Can't call bigint\-\>$name, not a valid method");
  47   }
  48
  49 sub upgrade
  50   {
  51   my $self = shift;
  52   no strict 'refs';
  53 #  if (defined $_[0])
  54 #    {
  55 #    $Math::BigInt::upgrade = $_[0];
  56 #    }
  57   return $Math::BigInt::upgrade;
  58   }
  59
  60 sub _constant
  61   {
  62   # this takes a floating point constant string and returns it truncated to
  63   # integer. For instance, '4.5' => '4', '1.234e2' => '123' etc
  64   my $float = shift;
  65
  66   # some simple cases first
  67   return $float if ($float =~ /^[+-]?[0-9]+$/);         # '+123','-1','0' etc
  68   return $float
  69     if ($float =~ /^[+-]?[0-9]+\.?[eE]\+?[0-9]+$/);     # 123e2, 123.e+2
  70   return '0' if ($float =~ /^[+-]?[0]*\.[0-9]+$/);      # .2, 0.2, -.1
  71   if ($float =~ /^[+-]?[0-9]+\.[0-9]*$/)                # 1., 1.23, -1.2 etc
  72     {
  73     $float =~ s/\..*//;
  74     return $float;
  75     }
  76   my ($mis,$miv,$mfv,$es,$ev) = Math::BigInt::_split($float);
  77   return $float if !defined $mis;       # doesn't look like a number to me
  78   my $ec = int($$ev);
  79   my $sign = $$mis; $sign = '' if $sign eq '+';
  80   if ($$es eq '-')
  81     {
  82     # ignore fraction part entirely
  83     if ($ec >= length($$miv))                   # 123.23E-4
  84       {
  85       return '0';
  86       }
  87     return $sign . substr ($$miv,0,length($$miv)-$ec);  # 1234.45E-2 = 12
  88     }
  89   # xE+y
  90   if ($ec >= length($$mfv))
  91     {
  92     $ec -= length($$mfv);
  93     return $sign.$$miv.$$mfv if $ec == 0;       # 123.45E+2 => 12345
  94     return $sign.$$miv.$$mfv.'E'.$ec;           # 123.45e+3 => 12345e1
  95     }
  96   $mfv = substr($$mfv,0,$ec);
  97   return $sign.$$miv.$mfv;                      # 123.45e+1 => 1234
  98   }
  99
 100 sub import
 101   {
 102   my $self = shift;
 103
 104   # some defaults
 105   my $lib = '';
 106
 107   my @import = ( ':constant' );                         # drive it w/ constant
 108   my @a = @_; my $l = scalar @_; my $j = 0;
 109   my ($ver,$trace);                                     # version? trace?
 110   my ($a,$p);                                           # accuracy, precision
 111   for ( my $i = 0; $i < $l ; $i++,$j++ )
 112     {
 113     if ($_[$i] =~ /^(l|lib)$/)
 114       {
 115       # this causes a different low lib to take care...
 116       $lib = $_[$i+1] || '';
 117       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
 118       splice @a, $j, $s; $j -= $s; $i++;
 119       }
 120     elsif ($_[$i] =~ /^(a|accuracy)$/)
 121       {
 122       $a = $_[$i+1];
 123       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
 124       splice @a, $j, $s; $j -= $s; $i++;
 125       }
 126     elsif ($_[$i] =~ /^(p|precision)$/)
 127       {
 128       $p = $_[$i+1];
 129       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
 130       splice @a, $j, $s; $j -= $s; $i++;
 131       }
 132     elsif ($_[$i] =~ /^(v|version)$/)
 133       {
 134       $ver = 1;
 135       splice @a, $j, 1; $j --;
 136       }
 137     elsif ($_[$i] =~ /^(t|trace)$/)
 138       {
 139       $trace = 1;
 140       splice @a, $j, 1; $j --;
 141       }
 142     else { die "unknown option $_[$i]"; }
 143     }
 144   my $class;
 145   $_lite = 0;                                   # using M::BI::L ?
 146   if ($trace)
 147     {
 148     require Math::BigInt::Trace; $class = 'Math::BigInt::Trace';
 149     }
 150   else
 151     {
 152     # see if we can find Math::BigInt::Lite
 153     if (!defined $a && !defined $p)             # rounding won't work to well
 154       {
 155       eval 'require Math::BigInt::Lite;';
 156       if ($@ eq '')
 157         {
 158         @import = ( );                          # :constant in Lite, not MBI
 159         Math::BigInt::Lite->import( ':constant' );
 160         $_lite= 1;                              # signal okay
 161         }
 162       }
 163     require Math::BigInt if $_lite == 0;        # not already loaded?
 164     $class = 'Math::BigInt';                    # regardless of MBIL or not
 165     }
 166   push @import, 'lib' => $lib if $lib ne '';
 167   # Math::BigInt::Trace or plain Math::BigInt
 168   $class->import(@import);
 169
 170   bigint->accuracy($a) if defined $a;
 171   bigint->precision($p) if defined $p;
 172   if ($ver)
 173     {
 174     print "bigint\t\t\t v$VERSION\n";
 175     print "Math::BigInt::Lite\t v$Math::BigInt::Lite::VERSION\n" if $_lite;
 176     print "Math::BigInt\t\t v$Math::BigInt::VERSION";
 177     my $config = Math::BigInt->config();
 178     print " lib => $config->{lib} v$config->{lib_version}\n";
 179     exit;
 180     }
 181   # we take care of floating point constants, since BigFloat isn't available
 182   # and BigInt doesn't like them:
 183   overload::constant float => sub { Math::BigInt->new( _constant(shift) ); };
 184
 185   $self->export_to_level(1,$self,@a);           # export inf and NaN
 186   }
 187
 188 sub inf () { Math::BigInt->binf(); }
 189 sub NaN () { Math::BigInt->bnan(); }
 190
 191 1;
 192
 193 __END__
 194
 195 =head1 NAME
 196
 197 bigint - Transparent BigInteger support for Perl
 198
 199 =head1 SYNOPSIS
 200
 201   use bigint;
 202
 203   $x = 2 + 4.5,"\n";                    # BigInt 6
 204   print 2 ** 512,"\n";                  # really is what you think it is
 205   print inf + 42,"\n";                  # inf
 206   print NaN * 7,"\n";                   # NaN
 207
 208 =head1 DESCRIPTION
 209
 210 All operators (including basic math operations) are overloaded. Integer
 211 constants are created as proper BigInts.
 212
 213 Floating point constants are truncated to integer. All results are also
 214 truncated.
 215
 216 =head2 Options
 217
 218 bigint recognizes some options that can be passed while loading it via use.
 219 The options can (currently) be either a single letter form, or the long form.
 220 The following options exist:
 221
 222 =over 2
 223
 224 =item a or accuracy
 225
 226 This sets the accuracy for all math operations. The argument must be greater
 227 than or equal to zero. See Math::BigInt's bround() function for details.
 228
 229         perl -Mbigint=a,2 -le 'print 12345+1'
 230
 231 =item p or precision
 232
 233 This sets the precision for all math operations. The argument can be any
 234 integer. Negative values mean a fixed number of digits after the dot, and
 235 are <B>ignored</B> since all operations happen in integer space.
 236 A positive value rounds to this digit left from the dot. 0 or 1 mean round to
 237 integer and are ignore like negative values.
 238
 239 See Math::BigInt's bfround() function for details.
 240
 241         perl -Mbignum=p,5 -le 'print 123456789+123'
 242
 243 =item t or trace
 244
 245 This enables a trace mode and is primarily for debugging bigint or
 246 Math::BigInt.
 247
 248 =item l or lib
 249
 250 Load a different math lib, see L<MATH LIBRARY>.
 251
 252         perl -Mbigint=l,GMP -e 'print 2 ** 512'
 253
 254 Currently there is no way to specify more than one library on the command
 255 line. This will be hopefully fixed soon ;)
 256
 257 =item v or version
 258
 259 This prints out the name and version of all modules used and then exits.
 260
 261         perl -Mbigint=v
 262
 263 =head2 Math Library
 264
 265 Math with the numbers is done (by default) by a module called
 266 Math::BigInt::Calc. This is equivalent to saying:
 267
 268         use bigint lib => 'Calc';
 269
 270 You can change this by using:
 271
 272         use bigint lib => 'BitVect';
 273
 274 The following would first try to find Math::BigInt::Foo, then
 275 Math::BigInt::Bar, and when this also fails, revert to Math::BigInt::Calc:
 276
 277         use bigint lib => 'Foo,Math::BigInt::Bar';
 278
 279 Please see respective module documentation for further details.
 280
 281 =head2 Internal Format
 282
 283 The numbers are stored as objects, and their internals might change at anytime,
 284 especially between math operations. The objects also might belong to different
 285 classes, like Math::BigInt, or Math::BigInt::Lite. Mixing them together, even
 286 with normal scalars is not extraordinary, but normal and expected.
 287
 288 You should not depend on the internal format, all accesses must go through
 289 accessor methods. E.g. looking at $x->{sign} is not a good idea since there
 290 is no guaranty that the object in question has such a hash key, nor is a hash
 291 underneath at all.
 292
 293 =head2 Sign
 294
 295 The sign is either '+', '-', 'NaN', '+inf' or '-inf'.
 296 You can access it with the sign() method.
 297
 298 A sign of 'NaN' is used to represent the result when input arguments are not
 299 numbers or as a result of 0/0. '+inf' and '-inf' represent plus respectively
 300 minus infinity. You will get '+inf' when dividing a positive number by 0, and
 301 '-inf' when dividing any negative number by 0.
 302
 303 =head2 Methods
 304
 305 Since all numbers are now objects, you can use all functions that are part of
 306 the BigInt API. You can only use the bxxx() notation, and not the fxxx()
 307 notation, though.
 308
 309 =head2 Caveat
 310
 311 But a warning is in order. When using the following to make a copy of a number,
 312 only a shallow copy will be made.
 313
 314         $x = 9; $y = $x;
 315         $x = $y = 7;
 316
 317 Using the copy or the original with overloaded math is okay, e.g. the
 318 following work:
 319
 320         $x = 9; $y = $x;
 321         print $x + 1, " ", $y,"\n";     # prints 10 9
 322
 323 but calling any method that modifies the number directly will result in
 324 B<both> the original and the copy beeing destroyed:
 325
 326         $x = 9; $y = $x;
 327         print $x->badd(1), " ", $y,"\n";        # prints 10 10
 328
 329         $x = 9; $y = $x;
 330         print $x->binc(1), " ", $y,"\n";        # prints 10 10
 331
 332         $x = 9; $y = $x;
 333         print $x->bmul(2), " ", $y,"\n";        # prints 18 18
 334
 335 Using methods that do not modify, but testthe contents works:
 336
 337         $x = 9; $y = $x;
 338         $z = 9 if $x->is_zero();                # works fine
 339
 340 See the documentation about the copy constructor and C<=> in overload, as
 341 well as the documentation in BigInt for further details.
 342
 343 =head1 MODULES USED
 344
 345 C<bigint> is just a thin wrapper around various modules of the Math::BigInt
 346 family. Think of it as the head of the family, who runs the shop, and orders
 347 the others to do the work.
 348
 349 The following modules are currently used by bigint:
 350
 351         Math::BigInt::Lite      (for speed, and only if it is loadable)
 352         Math::BigInt
 353
 354 =head1 EXAMPLES
 355
 356 Some cool command line examples to impress the Python crowd ;) You might want
 357 to compare them to the results under -Mbignum or -Mbigrat:
 358
 359         perl -Mbigint -le 'print sqrt(33)'
 360         perl -Mbigint -le 'print 2*255'
 361         perl -Mbigint -le 'print 4.5+2*255'
 362         perl -Mbigint -le 'print 3/7 + 5/7 + 8/3'
 363         perl -Mbigint -le 'print 123->is_odd()'
 364         perl -Mbigint -le 'print log(2)'
 365         perl -Mbigint -le 'print 2 ** 0.5'
 366         perl -Mbigint=a,65 -le 'print 2 ** 0.2'
 367
 368 =head1 LICENSE
 369
 370 This program is free software; you may redistribute it and/or modify it under
 371 the same terms as Perl itself.
 372
 373 =head1 SEE ALSO
 374
 375 Especially L<bigrat> as in C<perl -Mbigrat -le 'print 1/3+1/4'> and
 376 L<bignum> as in C<perl -Mbignum -le 'print sqrt(2)'>.
 377
 378 L<Math::BigInt>, L<Math::BigRat> and L<Math::Big> as well
 379 as L<Math::BigInt::BitVect>, L<Math::BigInt::Pari> and  L<Math::BigInt::GMP>.
 380
 381 =head1 AUTHORS
 382
 383 (C) by Tels L<http://bloodgate.com/> in early 2002 - 2005.
 384
 385 =cut