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Perl Documentation


bigrat - Transparent BigNumber/BigRational support for Perl


use bigrat;
print 2 + 4.5,"\n";                   # BigFloat 6.5
print 1/3 + 1/4,"\n";                 # produces 7/12
  no bigrat;
  print 1/3,"\n";                     # 0.33333...
# Import into current package:
use bigrat qw/hex oct/;
print hex("0x1234567890123490"),"\n";
print oct("01234567890123490"),"\n";


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

Other than bignum, this module upgrades to Math::BigRat, meaning that instead of 2.5 you will get 2+1/2 as output.

Modules Used

bigrat 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 Library

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

use bigrat lib => 'Calc';

You can change this by using:

use bignum lib => 'GMP';

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 bigrat lib => 'Foo,Math::BigInt::Bar';

Using lib warns if none of the specified libraries can be found and Math::BigInt did fall back to one of the default libraries. To suppress this warning, use try instead:

use bignum try => 'GMP';

If you want the code to die instead of falling back, use only instead:

use bignum only => 'GMP';

Please see respective module documentation for further details.


The sign is either '+', '-', 'NaN', '+inf' or '-inf'.

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.


Since all numbers are not 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 you independent on the fact that the underlying object might morph into a different class than BigFloat.


Math with the numbers is done (by default) by a module called


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;

If you want to make a real copy, use the following:

$y = $x->copy();

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 being 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.


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:



perl -Mbigrat -le 'print sqrt(33)'
perl -Mbigrat -le 'print 2*255'
perl -Mbigrat -le 'print 4.5+2*255'
perl -Mbigrat -le 'print 3/7 + 5/7 + 8/3'
perl -Mbigrat -le 'print 12->is_odd()';
perl -Mbignum=l,GMP -le 'print 7 ** 7777'


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


Especially bignum.

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


(C) by Tels in early 2002 - 2007.