NAME

       Math::Gradient - Perl extension for calculating gradients for colour transitions, etc.

SYNOPSIS

       use Math::Gradient qw(multi_gradient);

       # make a 100-point colour palette to smothly transition between 6 RGB values

       my(@hot_spots) = ([ 0, 255, 0 ], [ 255, 255, 0 ], [ 127, 127, 127 ], [ 0, 0, 255 ], [ 127,
       0, 0 ], [ 255, 255, 255 ]);

       my(@gradient) = multi_array_gradient(100, @hot_spots);

DESCRIPTION

       Math::Gradient is used to calculate smooth transitions between numerical values (also
       known as a "Gradient"). I wrote this module mainly to mix colours, but it probably has
       several other applications. Methods are supported to handle both basic and multiple-point
       gradients, both with scalars and arrays.

FUNCTIONS

       gradient($start_value, $end_value, $steps)
           This function will return an array of evenly distributed values between $start_value
           and $end_value. All three values supplied should be numeric. $steps should be the
           number of steps that should occur  between the two points; for instance, gradient(0,
           10, 4) would return the array (2, 4, 6, 8); the 4 evenly-distributed steps necessary
           to get from 0 to 10, whereas gradient(0, 1, 3) would return (0.25, 0.5, 0.75). This is
           the basest function in the Math::Gradient module and isn't very exciting, but all of
           the other functions below derive their work from it.

       array_gradient($start_value, $end_value, $steps)
           While gradient() takes numeric values for $start_value and $end_value,
           array_gradient() takes arrayrefs instead. The arrays supplied are expected to be lists
           of numerical values, and all of the arrays should contain the same number of elements.
           array_gradient() will return a list of arrayrefs signifying the gradient of all values
           on the lists $start_value and $end_value.

           For example, calling array_gradient([ 0, 100, 2 ], [ 100, 50, 70], 3) would return: ([
           25, 87.5, 19 ], [ 50, 75, 36 ], [ 75, 62.5, 53 ]).

       multi_gradient($steps, @values)
           multi_gradient() calculates multiple gradients at once, returning one list that is an
           even transition between all points, with the values supplied interpolated evenly
           within the list. If $steps is less than the number of entries in the list @values,
           items are deleted from @values instead.

           For example, calling multi_gradient(10, 0, 100, 50) would return: (0, 25, 50, 75, 100,
           90, 80, 70, 60, 50)

       multi_array_gradient($steps, @values)
           multi_array_gradient() is the same as multi_gradient, except that it works on
           arrayrefs instead of scalars (like array_gradient() is to gradient()).

AUTHOR

       Tyler MacDonald, <japh@crackerjack.net>

COPYRIGHT AND LICENSE

       Copyright 2003 by Tyler MacDonald

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