Math::CPWLF - interpolation using nested continuous piece-wise linear functions
Math::CPWLF provides an interface for defining continuous piece-wise linear functions by setting knots with x,y pairs.
use Math::CPWLF; $func = Math::CPWLF->new; $func->knot( 0 => 0 ); ## set the knot at f(0) equal to 0 $func->knot( 1 => 2 ); ## set the knot at f(1) equal to 2 $y = $func->( 0.5 ); ## interpolate f(0.5) ($y == 1)
Functions can be used in multiple dimensions, by specifying a
Math::CPWLF object as the y value of a knot.
$nested_func = Math::CPWLF->new; $nested_func->knot( 0 => 0 ); $nested_func->knot( 1 => 3 ); $func->knot( 2 => $nested_func ); $deep_y = $func->( 1.5 )( 0.5 ); ## $deep_y == 1.75
As a convenience, you can specify arbitrarily deep knots by passing more than two values two the
$func->knot( 2, 2 => 4 ); ## same as $nested_func->( 2 => 4);
If any of the intermediate knots do not exist they will be autovivified as
Math::CPWLF objects, much like perl hashes.
$func->knot( 3, 2 => 4 ); ## autovivify top level f(3)
Construct a new
Math::CPWLF function with no knots, and the default out of bounds behavior.
my $func = Math::CPWLF->new;
oob parameter controls how a function behaves when a given x value is out of bounds of the current minimum and maximum knots. If a function defines an
oob method in its constructor, that method is also used for any nested functions that were not explicitly constructed with their own
die- Throw an exception (default).
extrapolate- Perform a linear extrapolation using the two nearest knots.
level- Return the y value of the nearest knot.
undef- Return undef.
Construct an instance that returns
undef or empty list when the requested x is out of bounds:
my $func = Math::CPWLF->new( oob => 'undef' );
This instance method adds a knot with the given x,y values.
$func->knot( $x => $y );
Knots can be specified at arbitrary depth and intermediate knots will autovivify as needed. There are two alternate syntaxes for setting deep knots. The first involves passing 3 or more values to the
knot() call, where the last value is the y value and the other values are the depth-ordered x values:
$func->knot( $x1, $x2, $x3 => $y );
The other syntax is a bit more hash-like in that it separates the x values. Note that it starts with invoking the
knot() method with no arguments.
$func->knot->($x1)($x2)( $x3 => $y );
<dan at boorstein.net>
Please report any bugs or feature requests to
bug-math-cpwlf at rt.cpan.org, or through the web interface at http://rt.cpan.org/NoAuth/ReportBug.html?Queue=Math-CPWLF. I will be notified, and then you'll automatically be notified of progress on your bug as I make changes.
You can find documentation for this module with the perldoc command.
You can also look for information at:
Copyright 2009 Dan Boorstein.
This program is free software; you can redistribute it and/or modify it under the terms of either: the GNU General Public License as published by the Free Software Foundation; or the Artistic License.
See http://dev.perl.org/licenses/ for more information.