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bigrat(3pm)                           Perl Programmers Reference Guide                           bigrat(3pm)



NAME
       bigrat - Transparent BigNumber/BigRational support for Perl

SYNOPSIS
         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";

DESCRIPTION
       All operators (including 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.

       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 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 Math::BigInt 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.

       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.

       inf()
         A shortcut to return Math::BigInt->binf(). Useful because Perl does not always handle bareword
         "inf" properly.

       NaN()
         A shortcut to return Math::BigInt->bnan(). Useful because Perl does not always handle bareword
         "NaN" properly.

       e
                 # perl -Mbigrat=e -wle 'print e'

         Returns Euler's number "e", aka exp(1).

       PI
                 # 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()
         Return the class that numbers are upgraded to, is in fact returning $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 LIBRARY

       Math with the numbers is done (by default) by a module called

       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 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.

       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 argument must be greater than or equal to zero.
         See Math::BigInt's 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.

       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 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.

       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 means the
         following does not work:

                 perl -Mbignum=l,GMP,Pari -e 'print 2 ** 512'

         This will be hopefully fixed soon ;)

       hex
         Override the built-in 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
         Override the built-in 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;".

       v or version
         This prints out the name and version of all modules used and then exits.

                 perl -Mbigrat=v

CAVAETS
       in_effect()
         This method only works on Perl v5.9.4 or later.

       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");

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()';
               perl -Mbignum=l,GMP -le 'print 7 ** 7777'

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 - 2007.



perl v5.10.0                                     2007-12-18                                      bigrat(3pm)