bigrat(3p) Perl Programmers Reference Guide bigrat(3p)
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 over
loaded. Integer and floatingpoint 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::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.
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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 func
tions 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 "="
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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 bignum.
Math::BigFloat, Math::BigInt, Math::BigRat and Math::Big
as well as Math::BigInt::BitVect, Math::BigInt::Pari and
Math::BigInt::GMP.
AUTHORS
(C) by Tels <http://bloodgate.com/>; in early 2002.
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