bigint - Transparent big integer support for Perl
use bignt; $x = 2 + 4.5,"\n"; # BigInt 6 print 2 ** 512; # really is what you think it is
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 trunctaed.
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:
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'
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'
This enables a trace mode and is primarily for debugging bigint or Math::BigInt.
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 ;)
This prints out the name and version of all modules used and then exits.
perl -Mbigint=v -e ''
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::BigInt::Calc:
use bigint lib => 'Foo,Math::BigInt::Bar';
Please see respective module documentation for further details.
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 bright idea since there is no guaranty that the object in question has such a hash key, nor is a hash underneath at all.
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.
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.
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
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'
This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
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::BigInt::BitVect, Math::BigInt::Pari and Math::BigInt::GMP.
(C) by Tels http://bloodgate.com/ in early 2002.