MirOS Manual: bigint(3p)


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

DESCRIPTION

     All operators (including basic math operations) are over-
     loaded. Integer constants are created as proper BigInts.

     Floating point constants are truncated to integer. All
     results are also truncated.

     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 argu-
       ment must be greater than or equal to zero. See
       Math::BigInt's bround() function for details.

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

     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, 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'

     t or trace
       This enables a trace mode and is primarily for debugging
       bigint or Math::BigInt.

     l or lib
       Load a different math lib, see "MATH LIBRARY".

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

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       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 -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 bigint 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 bigint lib => 'Foo,Math::BigInt::Bar';

     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 under-
     neath 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

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     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.

     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;

     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:

             $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.

MODULES USED

     "bigint" 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.

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     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'

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 - 2005.

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