DOC HOME SITE MAP MAN PAGES GNU INFO SEARCH PRINT BOOK
 

bigint(3)





NAME

       bigint - Transparent BigInteger support for Perl


SYNOPSIS

         use bigint;

         $x = 2 + 4.5,"\n";                    # BigInt 6
         print 2 ** 512,"\n";                  # really is what you think it is
         print inf + 42,"\n";                  # inf
         print NaN * 7,"\n";                   # NaN


DESCRIPTION

       All operators (including basic math operations) are overloaded. Integer
       constants are created as proper BigInts.

       Floating point constants are truncated to integer. All results are also
       truncated.

       Options

       bigint recognizes some options that can be passed while loading it via
       use.  The options can (currently) be either a single letter form, or
       the long form.  The following options exist:

       a or accuracy
         This sets the accuracy for all math operations. The argument must be
         greater than or equal to zero. See Math::BigInt's bround() function
         for details.

                 perl -Mbigint=a,2 -le 'print 12345+1'

       p or precision
         This sets the precision for all math operations. The argument can be
         any integer. Negative values mean a fixed number of digits after the
         dot, and are <B>ignored</B> since all operations happen in integer
         space.  A positive value rounds to this digit left from the dot. 0 or
         1 mean round to integer and are ignore like negative values.

         See Math::BigInt's bfround() function for details.

                 perl -Mbignum=p,5 -le 'print 123456789+123'

       t or trace
         This enables a trace mode and is primarily for debugging bigint or
         Math::BigInt.

       l or lib
         Load a different math lib, see "MATH LIBRARY".

                 perl -Mbigint=l,GMP -e 'print 2 ** 512'

         Currently there is no way to specify more than one library on the
         command line. This will be hopefully fixed soon ;)

       v or version
         This prints out the name and version of all modules used and then
         exits.

                 perl -Mbigint=v

       Math Library

       Math with the numbers is done (by default) by a module called
       Math::BigInt::Calc. This is equivalent to saying:

               use bigint lib => 'Calc';

       You can change this by using:

               use bigint lib => 'BitVect';

       The following would first try to find Math::BigInt::Foo, then
       Math::BigInt::Bar, and when this also fails, revert to Math::Big-
       Int::Calc:

               use bigint lib => 'Foo,Math::BigInt::Bar';

       Please see respective module documentation for further details.

       Internal Format

       The numbers are stored as objects, and their internals might change at
       anytime, especially between math operations. The objects also might
       belong to different classes, like Math::BigInt, or Math::BigInt::Lite.
       Mixing them together, even with normal scalars is not extraordinary,
       but normal and expected.

       You should not depend on the internal format, all accesses must go
       through accessor methods. E.g. looking at $x->{sign} is not a good idea
       since there is no guaranty that the object in question has such a hash
       key, nor is a hash underneath at all.

       Sign

       The sign is either '+', '-', 'NaN', '+inf' or '-inf'.  You can access
       it with the sign() method.

       A sign of 'NaN' is used to represent the result when input arguments
       are not numbers or as a result of 0/0. '+inf' and '-inf' represent plus
       respectively minus infinity. You will get '+inf' when dividing a posi-
       tive number by 0, and '-inf' when dividing any negative number by 0.

       Methods

       Since all numbers are now objects, you can use all functions that are
       part of the BigInt API. You can only use the bxxx() notation, and not
       the fxxx() notation, though.

       Caveat

       But a warning is in order. When using the following to make a copy of a
       number, only a shallow copy will be made.

               $x = 9; $y = $x;
               $x = $y = 7;

       Using the copy or the original with overloaded math is okay, e.g. the
       following work:

               $x = 9; $y = $x;
               print $x + 1, " ", $y,"\n";     # prints 10 9

       but calling any method that modifies the number directly will result in
       both the original and the copy beeing destroyed:

               $x = 9; $y = $x;
               print $x->badd(1), " ", $y,"\n";        # prints 10 10

               $x = 9; $y = $x;
               print $x->binc(1), " ", $y,"\n";        # prints 10 10

               $x = 9; $y = $x;
               print $x->bmul(2), " ", $y,"\n";        # prints 18 18

       Using methods that do not modify, but testthe contents works:

               $x = 9; $y = $x;
               $z = 9 if $x->is_zero();                # works fine

       See the documentation about the copy constructor and "=" in overload,
       as well as the documentation in BigInt for further details.


MODULES USED

       "bigint" is just a thin wrapper around various modules of the
       Math::BigInt family. Think of it as the head of the family, who runs
       the shop, and orders the others to do the work.

       The following modules are currently used by bigint:

               Math::BigInt::Lite      (for speed, and only if it is loadable)
               Math::BigInt


EXAMPLES

       Some cool command line examples to impress the Python crowd ;) You
       might want to compare them to the results under -Mbignum or -Mbigrat:

               perl -Mbigint -le 'print sqrt(33)'
               perl -Mbigint -le 'print 2*255'
               perl -Mbigint -le 'print 4.5+2*255'
               perl -Mbigint -le 'print 3/7 + 5/7 + 8/3'
               perl -Mbigint -le 'print 123->is_odd()'
               perl -Mbigint -le 'print log(2)'
               perl -Mbigint -le 'print 2 ** 0.5'
               perl -Mbigint=a,65 -le 'print 2 ** 0.2'


LICENSE

       This program is free software; you may redistribute it and/or modify it
       under the same terms as Perl itself.


SEE ALSO

       Especially bigrat as in "perl -Mbigrat -le 'print 1/3+1/4'" and bignum
       as in "perl -Mbignum -le 'print sqrt(2)'".

       Math::BigInt, Math::BigRat and Math::Big as well as Math::Big-
       Int::BitVect, Math::BigInt::Pari and  Math::BigInt::GMP.


AUTHORS

       (C) by Tels <http://bloodgate.com/> in early 2002 - 2005.

perl v5.8.8                       2006-06-14                         bigint(3)

Man(1) output converted with man2html