


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


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:



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               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.




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


       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:



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


               $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.



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


       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");
                 }



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


         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.


























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