NAME
    Math::Erf::Approx - pure Perl approximate implementation of the error
    function

DESCRIPTION
    This is a pure Perl implementation of the error function (a.k.a. the
    Gauss error function). It gives an approximation with a maximum absolute
    difference of 0.0005 from the real value.

  Functions
    This module can export two functions. Neither is exported by default.
    This module uses Sub::Exporter, so the functions can be renamed:

     use Math::Erf::Approx -all => { -prefix => 'math_' };

    "erf($x)"
        Calculates the result of the error function for value $x.

    "erfc($x, \&erf)"
        Given a value $x and a code reference to an implementation of erf(),
        calculates the complement.

        If the code reference is ommitted (which I'd expect would be the
        most usual case), then the default is the "erf" function provided by
        this module.

  Testing
    It is possible to run a small test suite on this module using:

     use Math::Erf::Approx;
     Math::Erf::Approx->run_tests;

BENCHMARKS
    Benchmarking against Games::Go::Erf (on a fairly underpowered
    netbook)...

     Benchmark: timing 100000 iterations of GGE, MEA...
       GGE:  6 wallclock secs ( 6.34 usr +  0.01 sys =  6.35 CPU) @ 15748.03/s (n=100000)
       MEA:  3 wallclock secs ( 2.71 usr +  0.00 sys =  2.71 CPU) @ 36900.37/s (n=100000)

    There are considerations other than raw speed though...

    *   Games::Go::Erf provides much more accurate results

    *   ... and it can calculate inverses

    *   ... but it has a dependency on Tk

    *   ... and it sets $[ to 1, which has been deprecated since Perl 5.12.

SEE ALSO
    <http://en.wikipedia.org/wiki/Error_function>.

    *Handbook of Mathematical Functions with Formulas, Graphs, and
    Mathematical Tables*, ed Milton Abramowitz and Irene Stegun. ISBN
    0-486-61272-4.

AUTHOR
    Toby Inkster <tobyink@cpan.org>.

COPYRIGHT AND LICENCE
    This software is copyright (c) 2012 by Toby Inkster.

    This is free software; you can redistribute it and/or modify it under
    the same terms as the Perl 5 programming language system itself.

DISCLAIMER OF WARRANTIES
    THIS PACKAGE IS PROVIDED "AS IS" AND WITHOUT ANY EXPRESS OR IMPLIED
    WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
    MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.

