bigrat - Transparent BigNumber/BigRational support for Perl

- NAME
- SYNOPSIS
- DESCRIPTION

- MODULES USED
- MATH LIBRARY
- SIGN
- METHODS
- CAVEAT

- EXAMPLES
- LICENSE
- SEE ALSO
- AUTHORS

# NAME

bigrat - Transparent BigNumber/BigRational support for Perl

# SYNOPSIS

      use bigrat;

      $x = 2 + 4.5,"\n";                    # BigFloat 6.5
      print 1/3 + 1/4,"\n";                 # produces 7/12

# DESCRIPTION

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

Other than the bignum manpage, 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::BigInt
            Math::BigFloat
            Math::BigRat

## 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 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.

## SIGN

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

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 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.

## 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.

# EXAMPLES

            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()';

# LICENSE

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

# SEE ALSO

Especially the bignum manpage.

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

# AUTHORS

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

bigrat - Transparent BigNumber/BigRational support for Perl