Perl 5 version 8.7 documentation
- SEE ALSO
bigrat - Transparent BigNumber/BigRational support for Perl
All operators (inlcuding 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.
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 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 bigrat 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 bigrat lib => 'Foo,Math::BigInt::Bar';
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 independed on the fact that the underlying object might morph into a different class than BigFloat.
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 beeing destroyed:
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:
- 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 -Mbigrat=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 -Mbigrat=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 -Mbigrat=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 -Mbigrat=v
- 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()';
This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
(C) by Tels http://bloodgate.com/ in early 2002 - 2005.