bignum(3)

NAME
bignum - Transparent BigNumber support for Perl

SYNOPSIS
  use bignum;

  $x = 2 + 4.5,"\n";                    # BigFloat 6.5
  print 2 ** 512 * 0.1;                 # really is what you think it is

DESCRIPTION
All operators (including basic math operations) are overloaded. Integer and floating-point constants are created as proper BigInts or BigFloats, respectively.

  OPTIONS
bignum 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 -Mbignum=a,50 -le 'print sqrt(20)'

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, while a positive value rounds to this digit left from the dot. 0 or 1 mean round to integer. See Math::BigInt's bfround() function for details.

            perl -Mbignum=p,-50 -le 'print sqrt(20)'

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

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

            perl -Mbignum=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 -Mbignum=v -e ''

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

        use bignum lib => 'Calc';

You can change this by using:

        use bignum lib => 'BitVect';

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 bignum 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::BigFLoat. 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 bright idea since there is no guaranty that the object in question has such a hashkey, nor is a hash underneath at all.

  SIGN
The sign is either '+', '-', 'NaN', '+inf' or '-inf' and stored seperately. 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 positive 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 or BigFloat API. It is wise to use only the bxxx() notation, and not the fxxx() notation, though. This makes it possible that the underlying object might morph into a different class than BigFloat.

MODULES USED
"bignum" 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 bignum:

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

EXAMPLES
Some cool command line examples to impress the Python crowd ;)

        perl -Mbignum -le 'print sqrt(33)'
        perl -Mbignum -le 'print 2*255'
        perl -Mbignum -le 'print 4.5+2*255'
        perl -Mbignum -le 'print 3/7 + 5/7 + 8/3'
        perl -Mbignum -le 'print 123->is_odd()'
        perl -Mbignum -le 'print log(2)'
        perl -Mbignum -le 'print 2 ** 0.5'
        perl -Mbignum=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'".

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

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