NAME
Math::Decimal - arithmetic in decimal
DESCRIPTION
This module performs basic arithmetic with arbitrary-precision numbers
expressed in decimal in ordinary Perl strings. The numbers can be
arbitrarily large, and can involve arbitrarily small fractions, and
all results are exact. This differs from Perl's standard arithmetic,
which is limited-precision binary (floating point) arithmetic. However,
because Perl performs implicit conversions between strings and numbers,
using decimal in the string form, it is extremely easy to exchange values
between this module and Perl's native arithmetic.
Although Perl's scalars have space to store a number directly, that is
not used here. This module operates only on the string part of scalars,
ignoring the Perlish numerics entirely. It is not confused by dualvars
(scalars with independent string and number values).
Numbers are represented in strings in a simple format, consisting of
optional sign, one or more integer digits, then optionally a dot (for
the decimal point) and one or more fractional digits. All representable
numbers have infinitely many acceptable representations (by adding leading
and trailing zero digits). The functions of this module consistently
return numbers in their shortest possible form.
This module is intended for situations where exact numeric behaviour
is important, and Perl's default arithmetic is inadequate because
fractions or large numbers are involved, but the arithmetic makes up
only a small part of the program's behaviour. In those situations, it
is convenient that the functions here operate directly on strings that
are useful elsewhere in the program. If arithmetic is a large part of
the program, it will probably be better to use specialised (non-string)
numeric object types, such as those of Math::GMP. These objects are less
convenient for interoperation, but arithmetic with them is more efficient.
If you need to represent arbitrary (non-decimal) fractions exactly,
such as 1/3, then this module is not suitable. In that case you need a
general rational arithmetic module, such as Math::BigRat. Be prepared
to pay a large performance penalty for it.
Most of this module is implemented in XS, with a pure Perl backup version
for systems that can't handle XS.
INSTALLATION
perl Build.PL
./Build
./Build test
./Build install
AUTHOR
Andrew Main (Zefram)
COPYRIGHT
Copyright (C) 2009, 2010 Andrew Main (Zefram)
LICENSE
This module is free software; you can redistribute it and/or modify it
under the same terms as Perl itself.