


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


NAME
       bigint - Transparent BigInteger support for Perl

SYNOPSIS
         use bigint;

         $x = 2 + 4.5,"\n";                    # BigInt 6
         print 2 ** 512,"\n";                  # really is what you think it is
         print inf + 42,"\n";                  # inf
         print NaN * 7,"\n";                   # NaN
         print hex("0x1234567890123490"),"\n"; # Perl v5.9.4 or later

         {
           no bigint;
           print 2 ** 256,"\n";                # a normal Perl scalar now
         }

         # Note that this will be global:
         use bigint qw/hex oct/;
         print hex("0x1234567890123490"),"\n";
         print oct("01234567890123490"),"\n";

DESCRIPTION
       All operators (including basic math operations) are
       overloaded. Integer constants are created as proper
       BigInts.

       Floating point constants are truncated to integer. All
       parts and results of expressions are also truncated.

       Unlike integer, this pragma creates integer constants that
       are only limited in their size by the available memory and
       CPU time.

   use integer vs. use bigint
       There is one small difference between "use integer" and
       "use bigint": the former will not affect assignments to
       variables and the return value of some functions. "bigint"
       truncates these results to integer too:

               # perl -Minteger -wle 'print 3.2'
               3.2
               # perl -Minteger -wle 'print 3.2 + 0'
               3
               # perl -Mbigint -wle 'print 3.2'
               3
               # perl -Mbigint -wle 'print 3.2 + 0'
               3

               # perl -Mbigint -wle 'print exp(1) + 0'
               2
               # perl -Mbigint -wle 'print exp(1)'
               2
               # perl -Minteger -wle 'print exp(1)'



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


               2.71828182845905
               # perl -Minteger -wle 'print exp(1) + 0'
               2

       In practice this makes seldom a difference as parts and
       results of expressions will be truncated anyway, but this
       can, for instance, affect the return value of subroutines:

               sub three_integer { use integer; return 3.2; }
               sub three_bigint { use bigint; return 3.2; }

               print three_integer(), " ", three_bigint(),"\n";        # prints "3.2 3"

   Options
       bigint 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 -Mbigint=a,2 -le 'print 12345+1'

         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, and are
         <B>ignored</B> since all operations happen in integer
         space.  A positive value rounds to this digit left from
         the dot. 0 or 1 mean round to integer and are ignore
         like negative values.

         See Math::BigInt's bfround() function for details.

                 perl -Mbignum=p,5 -le 'print 123456789+123'

         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
         bigint or Math::BigInt.

       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;".



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


       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;".

       l, lib, try or only
         Load a different math lib, see "Math Library".

                 perl -Mbigint=lib,GMP -e 'print 2 ** 512'
                 perl -Mbigint=try,GMP -e 'print 2 ** 512'
                 perl -Mbigint=only,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 ;)

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

                 perl -Mbigint=v

   Math Library
       Math with the numbers is done (by default) by a module
       called Math::BigInt::Calc. This is equivalent to saying:

               use bigint 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 bigint 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';



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


       Please see respective module documentation for further
       details.

   Internal Format
       The numbers are stored as objects, and their internals
       might change at anytime, especially between math
       operations. The objects also might belong to different
       classes, like Math::BigInt, or Math::BigInt::Lite. Mixing
       them together, even with normal scalars is not
       extraordinary, but normal and expected.

       You should not depend on the internal format, all accesses
       must go through accessor methods. E.g. looking at
       $x->{sign} is not a good idea since there is no guaranty
       that the object in question has such a hash key, nor is a
       hash underneath at all.

   Sign
       The sign is either '+', '-', 'NaN', '+inf' or '-inf'.  You
       can access it with the sign() method.

       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 now objects, you can use all
       functions that are part of the BigInt API. You can only
       use the bxxx() notation, and not the fxxx() notation,
       though.

       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 -Mbigint=e -wle 'print e'

         Returns Euler's number "e", aka exp(1). Note that under
         bigint, this is truncated to an integer, and hence
         simple '2'.

       PI
                 # perl -Mbigint=PI -wle 'print PI'

         Returns PI. Note that under bigint, this is truncated to



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


         an integer, and hence simple '3'.

       bexp()
                 bexp($power,$accuracy);

         Returns Euler's number "e" raised to the appropriate
         power, to the wanted accuracy.

         Note that under bigint, the result is truncated to an
         integer.

         Example:

                 # perl -Mbigint=bexp -wle 'print bexp(1,80)'

       bpi()
                 bpi($accuracy);

         Returns PI to the wanted accuracy. Note that under
         bigint, this is truncated to an integer, and hence
         simple '3'.

         Example:

                 # perl -Mbigint=bpi -wle 'print bpi(80)'

       upgrade()
         Return the class that numbers are upgraded to, is in
         fact returning $Math::BigInt::upgrade.

       in_effect()
                 use bigint;

                 print "in effect\n" if bigint::in_effect;       # true
                 {
                   no bigint;
                   print "in effect\n" if bigint::in_effect;     # false
                 }

         Returns true or false if "bigint" 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

   Caveat
       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;



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


       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.

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:




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


                 use bigint;

                 # will warn only under Perl older than v5.9.4
                 print hex("0x1234567890123456");

MODULES USED
       "bigint" 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 bigint:

               Math::BigInt::Lite      (for speed, and only if it is loadable)
               Math::BigInt

EXAMPLES
       Some cool command line examples to impress the Python
       crowd ;) You might want to compare them to the results
       under -Mbignum or -Mbigrat:

               perl -Mbigint -le 'print sqrt(33)'
               perl -Mbigint -le 'print 2*255'
               perl -Mbigint -le 'print 4.5+2*255'
               perl -Mbigint -le 'print 3/7 + 5/7 + 8/3'
               perl -Mbigint -le 'print 123->is_odd()'
               perl -Mbigint -le 'print log(2)'
               perl -Mbigint -le 'print 2 ** 0.5'
               perl -Mbigint=a,65 -le 'print 2 ** 0.2'
               perl -Mbignum=a,65,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 bigrat as in "perl -Mbigrat -le 'print
       1/3+1/4'" and bignum as in "perl -Mbignum -le 'print
       sqrt(2)'".

       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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