bigrat(3p) Perl Programmers Reference Guide bigrat(3p)NAMEbigrat - 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 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.
Modules Used
"bigrat" is just a thin wrapper around various modules of
the Math::BigInt family. Think of it as the head of the fam-
ily, 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'.
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.
Cavaet
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 des-
troyed:
$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), " ", $y,"\n"; # prints 18 18
Using methods that do not modify, but testthe contents
works:
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$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.
Options
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 argu-
ment 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 argu-
ment 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
EXAMPLESperl v5.8.8 2005-02-05 3
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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 - 2005.
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