bigrat - Transparent BigNumber/BigRational support for Perl |
bigrat - Transparent BigNumber/BigRational support for Perl
use bigrat;
print 2 + 4.5,"\n"; # BigFloat 6.5 print 1/3 + 1/4,"\n"; # produces 7/12
{ no bigrat; print 1/3,"\n"; # 0.33333... }
# Note that this will make hex() and oct() be globally overriden: use bigrat qw/hex oct/; print hex("0x1234567890123490"),"\n"; print oct("01234567890123490"),"\n";
All operators (including 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.
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 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 bignum lib => 'GMP';
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';
Using lib
warns if none of the specified libraries can be found and
the Math::BigInt manpage did fall back to one of the default libraries.
To supress this warning, use try
instead:
use bignum try => 'GMP';
If you want the code to die instead of falling back, use only
instead:
use bignum only => 'GMP';
Please see respective module documentation for further details.
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.
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.
inf()
inf
properly.
NaN()
NaN
properly.
# perl -Mbigrat=e -wle 'print e'
Returns Euler's number e
, aka exp(1).
# perl -Mbigrat=PI -wle 'print PI'
Returns PI.
bexp()
bexp($power,$accuracy);
Returns Euler's number e
raised to the appropriate power, to
the wanted accuracy.
Example:
# perl -Mbigrat=bexp -wle 'print bexp(1,80)'
bpi()
bpi($accuracy);
Returns PI to the wanted accuracy.
Example:
# perl -Mbigrat=bpi -wle 'print bpi(80)'
upgrade()
$Math::BigInt::upgrade
.
in_effect()
use bigrat;
print "in effect\n" if bigrat::in_effect; # true { no bigrat; print "in effect\n" if bigrat::in_effect; # false }
Returns true or false if bigrat
is in effect in the current scope.
This method only works on Perl v5.9.4 or later.
Math with the numbers is done (by default) by a module called
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 being 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.
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:
bround()
function for details.
perl -Mbigrat=a,50 -le 'print sqrt(20)'
Note that setting precision and accurary at the same time is not possible.
bfround()
function for details.
perl -Mbigrat=p,-50 -le 'print sqrt(20)'
Note that setting precision and accurary at the same time is not possible.
perl -Mbigrat=l,GMP -e 'print 2 ** 512'
Currently there is no way to specify more than one library on the command line. This means the following does not work:
perl -Mbignum=l,GMP,Pari -e 'print 2 ** 512'
This will be hopefully fixed soon ;)
hex()
method with a version that can handle big
integers. Note that under Perl v5.9.4 or ealier, this will be global
and cannot be disabled with ``no bigint;''.
oct()
method with a version that can handle big
integers. Note that under Perl v5.9.4 or ealier, this will be global
and cannot be disabled with ``no bigint;''.
perl -Mbigrat=v
in_effect()
hex()/oct()
bigint
overrides these routines with versions that can also handle
big integer values. Under Perl prior to version v5.9.4, however, this
will not happen unless you specifically ask for it with the two
import tags ``hex'' and ``oct'' - and then it will be global and cannot be
disabled inside a scope with ``no bigint'':
use bigint qw/hex oct/;
print hex("0x1234567890123456"); { no bigint; print hex("0x1234567890123456"); }
The second call to hex()
will warn about a non-portable constant.
Compare this to:
use bigint;
# will warn only under Perl older than v5.9.4 print hex("0x1234567890123456");
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()'; perl -Mbignum=l,GMP -le 'print 7 ** 7777'
This program is free software; you may redistribute it and/or modify it under the same terms as Perl itself.
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.
(C) by Tels http://bloodgate.com/ in early 2002 - 2007.
bigrat - Transparent BigNumber/BigRational support for Perl |