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bigint(3)


NAME

  bigint - Transparent BigInteger support for Perl


SYNOPSIS

    use bignt;

    $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 overloaded. 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 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'

  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'

  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'

    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 -e ''

  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 underneath at all.

  SIGN

  The sign is either '+', '-', 'NaN', '+inf' or '-inf' and stored seperately.
  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.

  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 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.


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'


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.

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