# phpman > man > 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...
      }

      # Import into current package:
      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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigRat/markdown), 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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown) 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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3ALite/markdown)      (for speed, and only if it is loadable)
            [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)
            [Math::BigFloat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigFloat/markdown)
            [Math::BigRat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigRat/markdown)

### Math Library
    Math with the numbers is done (by default) by a module called [Math::BigInt::Calc](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3ACalc/markdown). 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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3AFoo/markdown), then [Math::BigInt::Bar](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3ABar/markdown), and when this
    also fails, revert to [Math::BigInt::Calc](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3ACalc/markdown):

            use bigrat lib => 'Foo,[Math::BigInt::Bar](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3ABar/markdown)';

    Using "lib" warns if none of the specified libraries can be found and [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown) did fall back
    to one of the default libraries. To suppress 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 independent on the fact that the underlying object might morph into a different
    class than BigFloat.

### inf
      A shortcut to return [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)->binf(). Useful because Perl does not always handle bareword
      "inf" properly.

    NaN()
      A shortcut to return [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)->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)](https://www.chedong.com/phpMan.php/man/exp/1/markdown).

    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)](https://www.chedong.com/phpMan.php/man/bpi/80/markdown)'

### upgrade
      Return the class that numbers are upgraded to, is in fact returning $[Math::BigInt::upgrade](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3Aupgrade/markdown).

### in_effect
              use bigrat;

              print "in effect\n" if [bigrat::in_effect](https://www.chedong.com/phpMan.php/perldoc/bigrat%3A%3Aineffect/markdown);       # true
              {
                no bigrat;
                print "in effect\n" if [bigrat::in_effect](https://www.chedong.com/phpMan.php/perldoc/bigrat%3A%3Aineffect/markdown);     # 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

### 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;

    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)](https://www.chedong.com/phpMan.php/man/badd/1/markdown), " ", $y,"\n";        # prints 10 10

            $x = 9; $y = $x;
            print $x->[binc(1)](https://www.chedong.com/phpMan.php/man/binc/1/markdown), " ", $y,"\n";        # prints 10 10

            $x = 9; $y = $x;
            print $x->[bmul(2)](https://www.chedong.com/phpMan.php/man/bmul/2/markdown), " ", $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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)'s bround() function for details.

              perl -Mbigrat=a,50 -le 'print [sqrt(20)](https://www.chedong.com/phpMan.php/man/sqrt/20/markdown)'

      Note that setting precision and accuracy 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](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)'s bfround() function
      for details.

              perl -Mbigrat=p,-50 -le 'print [sqrt(20)](https://www.chedong.com/phpMan.php/man/sqrt/20/markdown)'

      Note that setting precision and accuracy at the same time is not possible.

    t or trace
      This enables a trace mode and is primarily for debugging bignum or
      [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)/[Math::BigFloat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigFloat/markdown).

    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 numbers. This overrides
      it by exporting it to the current package. Under Perl v5.10.0 and higher, this is not so
      necessary, as hex() is lexically overridden in the current scope whenever the bigrat pragma is
      active.

    oct
      Override the built-in oct() method with a version that can handle big numbers. This overrides
      it by exporting it to the current package. Under Perl v5.10.0 and higher, this is not so
      necessary, as oct() is lexically overridden in the current scope whenever the bigrat pragma is
      active.

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

              perl -Mbigrat=v

## CAVEATS
    Operator vs literal overloading
      "bigrat" works by overloading handling of integer and floating point literals, converting them
      to [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown) or [Math::BigRat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigRat/markdown) objects.

      This means that arithmetic involving only string values or string literals will be performed
      using Perl's built-in operators.

      For example:

          use bigrat;
          my $x = "900000000000000009";
          my $y = "900000000000000007";
          print $x - $y;

      will output 0 on default 32-bit builds, since "bigrat" never sees the string literals. To
      ensure the expression is all treated as "[Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown)" or "[Math::BigRat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigRat/markdown)" objects, use a
      literal number in the expression:

          print +(0+$x) - $y;

### in_effect
      This method only works on Perl v5.9.4 or later.

### hex
      "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)](https://www.chedong.com/phpMan.php/man/sqrt/33/markdown)'
            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'

## BUGS
    For information about bugs and how to report them, see the BUGS section in the documentation
    available with the perldoc command.

        perldoc bignum

## SUPPORT
    You can find documentation for this module with the perldoc command.

        perldoc bigrat

    For more information, see the SUPPORT section in the documentation available with the perldoc
    command.

        perldoc bignum

## LICENSE
    This program is free software; you may redistribute it and/or modify it under the same terms as
    Perl itself.

## SEE ALSO
    bignum and bigint.

    [Math::BigInt](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt/markdown), [Math::BigFloat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigFloat/markdown), [Math::BigRat](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigRat/markdown) and [Math::Big](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABig/markdown) as well as [Math::BigInt::FastCalc](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3AFastCalc/markdown),
    [Math::BigInt::Pari](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3APari/markdown) and [Math::BigInt::GMP](https://www.chedong.com/phpMan.php/perldoc/Math%3A%3ABigInt%3A%3AGMP/markdown).

## AUTHORS
    *   (C) by Tels <<http://bloodgate.com/>> in early 2002 - 2007.

    *   Peter John Acklam <<pjacklam@gmail.com><gt>, 2014-.