Daniel B. Boorstein >
Math-CPWLF >
Math::CPWLF

Module Version: 0.15
Math::CPWLF - interpolation using nested continuous piece-wise linear functions

Version 0.15

`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 `knot`

method.

$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;

Optional parameters:

- oob
The

`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`oob`

methods.`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 Boorstein, `<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.

perldoc Math::CPWLF

You can also look for information at:

- RT: CPAN's request tracker
- AnnoCPAN: Annotated CPAN documentation
- CPAN Ratings
- Search CPAN

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.

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