MirOS Manual: bigrat(3p)


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 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

EXAMPLES


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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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