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bigrat(3) Perl Programmers Reference Guide bigrat(3)
NNAAMMEE
bigrat - Transparent BigNumber/BigRational support for Perl
SSYYNNOOPPSSIISS
use bigrat;
$x = 2 + 4.5,"\n"; # BigFloat 6.5
print 1/3 + 1/4,"\n"; # produces 7/12
DDEESSCCRRIIPPTTIIOONN
All operators (inlcuding basic math operations) are overloaded. 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.
MMoodduulleess UUsseedd
"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
MMaatthh LLiibbrraarryy
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::Big-
Int::Calc:
use bigrat lib => 'Foo,Math::BigInt::Bar';
Please see respective module documentation for further details.
SSiiggnn
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 posi-
tive number by 0, and '-inf' when dividing any negative number by 0.
MMeetthhooddss
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 _b_x_x_x_(_)
notation, and not the _f_x_x_x_(_) notation, though. This makes you inde-
pended on the fact that the underlying object might morph into a dif-
ferent class than BigFloat.
CCaavvaaeett
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
bbootthh 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.
OOppttiioonnss
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 argument must be
greater than or equal to zero. See Math::BigInt's _b_r_o_u_n_d_(_) function
for details.
perl -Mbigrat=a,50 -le 'print sqrt(20)'
p or precision
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, while a positive value rounds to this digit left from the dot. 0
or 1 mean round to integer. See Math::BigInt's _b_f_r_o_u_n_d_(_) 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
EEXXAAMMPPLLEESS
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()';
LLIICCEENNSSEE
This program is free software; you may redistribute it and/or modify it
under the same terms as Perl itself.
SSEEEE AALLSSOO
Especially bignum.
Math::BigFloat, Math::BigInt, Math::BigRat and Math::Big as well as
Math::BigInt::BitVect, Math::BigInt::Pari and Math::BigInt::GMP.
AAUUTTHHOORRSS
(C) by Tels in early 2002 - 2005.
perl v5.8.8 2006-06-14 bigrat(3)