lib/perl5/5.8.8/bigrat.pm

   1 package bigrat;
   2 require 5.005;
   3
   4 $VERSION = '0.08';
   5 require Exporter;
   6 @ISA            = qw( Exporter );
   7 @EXPORT_OK      = qw( );
   8 @EXPORT         = qw( inf NaN );
   9
  10 use strict;
  11
  12 ##############################################################################
  13
  14 # These are all alike, and thus faked by AUTOLOAD
  15
  16 my @faked = qw/round_mode accuracy precision div_scale/;
  17 use vars qw/$VERSION $AUTOLOAD $_lite/;         # _lite for testsuite
  18
  19 sub AUTOLOAD
  20   {
  21   my $name = $AUTOLOAD;
  22
  23   $name =~ s/.*:://;    # split package
  24   no strict 'refs';
  25   foreach my $n (@faked)
  26     {
  27     if ($n eq $name)
  28       {
  29       *{"bigrat::$name"} = sub
  30         {
  31         my $self = shift;
  32         no strict 'refs';
  33         if (defined $_[0])
  34           {
  35           Math::BigInt->$name($_[0]);
  36           Math::BigFloat->$name($_[0]);
  37           return Math::BigRat->$name($_[0]);
  38           }
  39         return Math::BigInt->$name();
  40         };
  41       return &$name;
  42       }
  43     }
  44
  45   # delayed load of Carp and avoid recursion
  46   require Carp;
  47   Carp::croak ("Can't call bigrat\-\>$name, not a valid method");
  48   }
  49
  50 sub upgrade
  51   {
  52   my $self = shift;
  53   no strict 'refs';
  54 #  if (defined $_[0])
  55 #    {
  56 #    $Math::BigInt::upgrade = $_[0];
  57 #    $Math::BigFloat::upgrade = $_[0];
  58 #    }
  59   return $Math::BigInt::upgrade;
  60   }
  61
  62 sub import
  63   {
  64   my $self = shift;
  65
  66   # see also bignum->import() for additional comments
  67
  68   # some defaults
  69   my $lib = ''; my $upgrade = 'Math::BigFloat';
  70
  71   my @import = ( ':constant' );                         # drive it w/ constant
  72   my @a = @_; my $l = scalar @_; my $j = 0;
  73   my ($a,$p);
  74   my ($ver,$trace);                                     # version? trace?
  75   for ( my $i = 0; $i < $l ; $i++,$j++ )
  76     {
  77     if ($_[$i] eq 'upgrade')
  78       {
  79       # this causes upgrading
  80       $upgrade = $_[$i+1];              # or undef to disable
  81       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
  82       splice @a, $j, $s; $j -= $s;
  83       }
  84     elsif ($_[$i] =~ /^(l|lib)$/)
  85       {
  86       # this causes a different low lib to take care...
  87       $lib = $_[$i+1] || '';
  88       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
  89       splice @a, $j, $s; $j -= $s; $i++;
  90       }
  91     elsif ($_[$i] =~ /^(a|accuracy)$/)
  92       {
  93       $a = $_[$i+1];
  94       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
  95       splice @a, $j, $s; $j -= $s; $i++;
  96       }
  97     elsif ($_[$i] =~ /^(p|precision)$/)
  98       {
  99       $p = $_[$i+1];
 100       my $s = 2; $s = 1 if @a-$j < 2;   # avoid "can not modify non-existant..."
 101       splice @a, $j, $s; $j -= $s; $i++;
 102       }
 103     elsif ($_[$i] =~ /^(v|version)$/)
 104       {
 105       $ver = 1;
 106       splice @a, $j, 1; $j --;
 107       }
 108     elsif ($_[$i] =~ /^(t|trace)$/)
 109       {
 110       $trace = 1;
 111       splice @a, $j, 1; $j --;
 112       }
 113     else
 114       {
 115       die ("unknown option $_[$i]");
 116       }
 117     }
 118   my $class;
 119   $_lite = 0;                                   # using M::BI::L ?
 120   if ($trace)
 121     {
 122     require Math::BigInt::Trace; $class = 'Math::BigInt::Trace';
 123     $upgrade = 'Math::BigFloat::Trace';
 124     }
 125   else
 126     {
 127     # see if we can find Math::BigInt::Lite
 128     if (!defined $a && !defined $p)             # rounding won't work to well
 129       {
 130       eval 'require Math::BigInt::Lite;';
 131       if ($@ eq '')
 132         {
 133         @import = ( );                          # :constant in Lite, not MBI
 134         Math::BigInt::Lite->import( ':constant' );
 135         $_lite= 1;                              # signal okay
 136         }
 137       }
 138     require Math::BigInt if $_lite == 0;        # not already loaded?
 139     $class = 'Math::BigInt';                    # regardless of MBIL or not
 140     }
 141   push @import, 'lib' => $lib if $lib ne '';
 142   # Math::BigInt::Trace or plain Math::BigInt
 143   $class->import(@import, upgrade => $upgrade);
 144
 145   require Math::BigFloat;
 146   Math::BigFloat->import( upgrade => 'Math::BigRat', ':constant' );
 147   require Math::BigRat;
 148
 149   bigrat->accuracy($a) if defined $a;
 150   bigrat->precision($p) if defined $p;
 151   if ($ver)
 152     {
 153     print "bigrat\t\t\t v$VERSION\n";
 154     print "Math::BigInt::Lite\t v$Math::BigInt::Lite::VERSION\n" if $_lite;
 155     print "Math::BigInt\t\t v$Math::BigInt::VERSION";
 156     my $config = Math::BigInt->config();
 157     print " lib => $config->{lib} v$config->{lib_version}\n";
 158     print "Math::BigFloat\t\t v$Math::BigFloat::VERSION\n";
 159     print "Math::BigRat\t\t v$Math::BigRat::VERSION\n";
 160     exit;
 161     }
 162   $self->export_to_level(1,$self,@a);           # export inf and NaN
 163   }
 164
 165 sub inf () { Math::BigInt->binf(); }
 166 sub NaN () { Math::BigInt->bnan(); }
 167
 168 1;
 169
 170 __END__
 171
 172 =head1 NAME
 173
 174 bigrat - Transparent BigNumber/BigRational support for Perl
 175
 176 =head1 SYNOPSIS
 177
 178   use bigrat;
 179
 180   $x = 2 + 4.5,"\n";                    # BigFloat 6.5
 181   print 1/3 + 1/4,"\n";                 # produces 7/12
 182
 183 =head1 DESCRIPTION
 184
 185 All operators (inlcuding basic math operations) are overloaded. Integer and
 186 floating-point constants are created as proper BigInts or BigFloats,
 187 respectively.
 188
 189 Other than L<bignum>, this module upgrades to Math::BigRat, meaning that
 190 instead of 2.5 you will get 2+1/2 as output.
 191
 192 =head2 Modules Used
 193
 194 C<bigrat> is just a thin wrapper around various modules of the Math::BigInt
 195 family. Think of it as the head of the family, who runs the shop, and orders
 196 the others to do the work.
 197
 198 The following modules are currently used by bignum:
 199
 200         Math::BigInt::Lite      (for speed, and only if it is loadable)
 201         Math::BigInt
 202         Math::BigFloat
 203         Math::BigRat
 204
 205 =head2 Math Library
 206
 207 Math with the numbers is done (by default) by a module called
 208 Math::BigInt::Calc. This is equivalent to saying:
 209
 210         use bigrat lib => 'Calc';
 211
 212 You can change this by using:
 213
 214         use bigrat lib => 'BitVect';
 215
 216 The following would first try to find Math::BigInt::Foo, then
 217 Math::BigInt::Bar, and when this also fails, revert to Math::BigInt::Calc:
 218
 219         use bigrat lib => 'Foo,Math::BigInt::Bar';
 220
 221 Please see respective module documentation for further details.
 222
 223 =head2 Sign
 224
 225 The sign is either '+', '-', 'NaN', '+inf' or '-inf'.
 226
 227 A sign of 'NaN' is used to represent the result when input arguments are not
 228 numbers or as a result of 0/0. '+inf' and '-inf' represent plus respectively
 229 minus infinity. You will get '+inf' when dividing a positive number by 0, and
 230 '-inf' when dividing any negative number by 0.
 231
 232 =head2 Methods
 233
 234 Since all numbers are not objects, you can use all functions that are part of
 235 the BigInt or BigFloat API. It is wise to use only the bxxx() notation, and not
 236 the fxxx() notation, though. This makes you independed on the fact that the
 237 underlying object might morph into a different class than BigFloat.
 238
 239 =head2 Cavaet
 240
 241 But a warning is in order. When using the following to make a copy of a number,
 242 only a shallow copy will be made.
 243
 244         $x = 9; $y = $x;
 245         $x = $y = 7;
 246
 247 If you want to make a real copy, use the following:
 248
 249         $y = $x->copy();
 250
 251 Using the copy or the original with overloaded math is okay, e.g. the
 252 following work:
 253
 254         $x = 9; $y = $x;
 255         print $x + 1, " ", $y,"\n";     # prints 10 9
 256
 257 but calling any method that modifies the number directly will result in
 258 B<both> the original and the copy beeing destroyed:
 259
 260         $x = 9; $y = $x;
 261         print $x->badd(1), " ", $y,"\n";        # prints 10 10
 262
 263         $x = 9; $y = $x;
 264         print $x->binc(1), " ", $y,"\n";        # prints 10 10
 265
 266         $x = 9; $y = $x;
 267         print $x->bmul(2), " ", $y,"\n";        # prints 18 18
 268
 269 Using methods that do not modify, but testthe contents works:
 270
 271         $x = 9; $y = $x;
 272         $z = 9 if $x->is_zero();                # works fine
 273
 274 See the documentation about the copy constructor and C<=> in overload, as
 275 well as the documentation in BigInt for further details.
 276
 277 =head2 Options
 278
 279 bignum recognizes some options that can be passed while loading it via use.
 280 The options can (currently) be either a single letter form, or the long form.
 281 The following options exist:
 282
 283 =over 2
 284
 285 =item a or accuracy
 286
 287 This sets the accuracy for all math operations. The argument must be greater
 288 than or equal to zero. See Math::BigInt's bround() function for details.
 289
 290         perl -Mbigrat=a,50 -le 'print sqrt(20)'
 291
 292 =item p or precision
 293
 294 This sets the precision for all math operations. The argument can be any
 295 integer. Negative values mean a fixed number of digits after the dot, while
 296 a positive value rounds to this digit left from the dot. 0 or 1 mean round to
 297 integer. See Math::BigInt's bfround() function for details.
 298
 299         perl -Mbigrat=p,-50 -le 'print sqrt(20)'
 300
 301 =item t or trace
 302
 303 This enables a trace mode and is primarily for debugging bignum or
 304 Math::BigInt/Math::BigFloat.
 305
 306 =item l or lib
 307
 308 Load a different math lib, see L<MATH LIBRARY>.
 309
 310         perl -Mbigrat=l,GMP -e 'print 2 ** 512'
 311
 312 Currently there is no way to specify more than one library on the command
 313 line. This will be hopefully fixed soon ;)
 314
 315 =item v or version
 316
 317 This prints out the name and version of all modules used and then exits.
 318
 319         perl -Mbigrat=v
 320
 321 =head1 EXAMPLES
 322
 323         perl -Mbigrat -le 'print sqrt(33)'
 324         perl -Mbigrat -le 'print 2*255'
 325         perl -Mbigrat -le 'print 4.5+2*255'
 326         perl -Mbigrat -le 'print 3/7 + 5/7 + 8/3'
 327         perl -Mbigrat -le 'print 12->is_odd()';
 328
 329 =head1 LICENSE
 330
 331 This program is free software; you may redistribute it and/or modify it under
 332 the same terms as Perl itself.
 333
 334 =head1 SEE ALSO
 335
 336 Especially L<bignum>.
 337
 338 L<Math::BigFloat>, L<Math::BigInt>, L<Math::BigRat> and L<Math::Big> as well
 339 as L<Math::BigInt::BitVect>, L<Math::BigInt::Pari> and  L<Math::BigInt::GMP>.
 340
 341 =head1 AUTHORS
 342
 343 (C) by Tels L<http://bloodgate.com/> in early 2002 - 2005.
 344
 345 =cut