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RalstonRabinowitz.php

<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4 foldmethod=marker: */

// {{{ Header

/**
 * Driver file contains Math_Numerical_RootFinding_Bisection class to provide
 * Ralston and Rabinowitz method root finding calculation.
 *
 * PHP versions 4 and 5
 *
 * LICENSE:
 *
 * BSD License
 *
 * Copyright (c) 2004-2006 Firman Wandayandi
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 * notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided
 * with the distribution.
 * 3. Neither the name of Firman Wandayandi nor the names of
 * contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
 * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
 * ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 *
 * @category Math
 * @package Math_Numerical_RootFinding
 * @subpackage Methods
 * @author Firman Wandayandi <firman@php.net>
 * @copyright Copyright (c) 2004-2006 Firman Wandayandi
 * @license http://www.opensource.org/licenses/bsd-license.php
 * BSD License
 * @version CVS: $Id: RalstonRabinowitz.php,v 1.1 2006/01/30 18:42:00 firman Exp $
 */

// }}}
// {{{ Dependencies

/**
 * Load Math_Numerical_RootFinding_Common as base class.
 */
require_once 'Math/Numerical/RootFinding/Common.php';

// }}}
// {{{ Class: Math_Numerical_RootFinding_RalstonRabinowitz

/**
 * Ralston and Rabinowitz method class.
 *
 * @category Math
 * @package Math_Numerical_RootFinding
 * @subpackage Methods
 * @author Firman Wandayandi <firman@php.net>
 * @copyright Copyright (c) 2004-2006 Firman Wandayandi
 * @license http://www.opensource.org/licenses/bsd-license.php
 * BSD License
 * @version Release: 1.0.0
 */
class Math_Numerical_RootFinding_RalstonRabinowitz
extends Math_Numerical_RootFinding_Common
{
 // {{{ Constructor

/**
     * Constructor.
     *
     * @param array $options (optional) Options.
     *
     * @access public
     * @see Math_Numerical_RootFinding_Common::Math_Numerical_RootFinding_Common()
     */
    function Math_Numerical_RootFinding_RalstonRabinowitz($options = null)
    {
        parent::Math_Numerical_RootFinding_Common($options);
    }

// }}}
    // {{{ infoCompute()

/**
 * Print out parameters description for compute() function.
 *
 * @access public
 */
 function infoCompute()
 {
 print "<h2>False Position::compute()</h2>\n" .

"float | PEAR_Error " .
 "compute(\$fxFunction, " .
 "\$dfxFunction, \$xR0, " .
 "\$xR1) \n" .

"<h3>Description</h3>\n" .
 "callback \$fxFunction Callback f(x) equation " .
 "function or object/method tuple. \n" .

"callback \$dfxFunction Callback f'(x) " .
 "equation function or object/method tuple. \n" .

"float \$xR0 First initial guess. \n" .

"float \$xR1 Second initial guess. \n";
 }

// }}}
    // {{{ compute()

/**
     * Ralston and Rabinowitz method for calculate double root (twin root).
     *
     * @param callback $fxFunction Callback f(x) equation function or
     *                             object/method tuple.
     * @param callback $dxFunction Callback f'(x) equation function or
     *                             object/method tuple.
     * @param float $xR0 First initial guess.
     * @param float $xR1 Second initial guess.
     *
     * @return float|PEAR_Error Root value on success or PEAR_Error on failure.
     * @access public
     * @see Math_Numerical_RootFinding_Common::validateEqFunction()
     * @see Math_Numerical_RootFinding_Common::getEqResult()
     * @see Math_Numerical_RootFinding_Common::isDivergentRow()
     * @see Math_Numerical_RootFinding_Secant::compute()
     */
    function compute($fxFunction, $dxFunction, $xR0, $xR1)
    {
        // Validate f(x) equation function.
        $err = Math_Numerical_RootFinding_Common::validateEqFunction($fxFunction);
        if (PEAR::isError($err)) {
            return $err;
        }

// Validate f'(x) equation function.
        $err = Math_Numerical_RootFinding_Common::validateEqFunction($dxFunction);
        if (PEAR::isError($err)) {
            return $err;
        }

// Sets maximum iteration and tolerance from options.
        $maxIteration = $this->options['max_iteration'];
        $errTolerance = $this->options['err_tolerance'];

// Sets variable for saving errors during iteration, for divergent
        // detection.
        $epsErrors = array();

for($i = 1; $i <= $maxIteration; $i++) {
 // Calculate f(x[i-1]) and f'(x[1]), where: x[i-1] = $xR0.
 $fxR0 = Math_Numerical_RootFinding_Common::getEqResult($fxFunction, $xR0);
 $dxR0 = Math_Numerical_RootFinding_Common::getEqResult($dxFunction, $xR0);

// Calculate f(x[i]) and f'(x[1]), where: x[i] = $xR1.
            $fxR1 = Math_Numerical_RootFinding_Common::getEqResult($fxFunction, $xR1);
            $dxR1 = Math_Numerical_RootFinding_Common::getEqResult($dxFunction, $xR1);

// Calculate f(x[i-1]) / f'(x[i-1], where x[i-1] = $xR0.
            $uxR0 = $fxR0 / $dxR0;

// Calculate f(x[i]) / f'(x[i]), where x[i] = $xR1;
            $uxR1 = $fxR1 / $dxR1;

// Avoid division by zero.
            if ($uxR0 - $uxR1 == 0) {
                return PEAR::raiseError('Iteration skipped division by zero');
            }

// Ralston and Rabinowitz's formula.
            $xN = $xR1 - ($uxR1 * ($xR0 - $xR1) / ($uxR0 - $uxR1));

// xR is the root.
            if ($xN == 0) {
                $this->root = $xR;
                break;
            }

// Compute error.
            $this->epsError = abs(($xN - $xR1) / $xN);
            $epsErrors[] = $this->epsError;

// Detect for divergent rows.
            if ($this->isDivergentRows($epsErrors) &&
                $this->options['divergent_skip'])
            {
                return PEAR::raiseError('Iteration skipped, divergent rows detected');
                break;
            }

// Check for error tolerance, if lower than or equal with
 // $errTolerance it is the root.
 if ($this->epsError <= $errTolerance) {
 $this->root = $xR1;
 break;
 }

// Swicth the values for next iteration x[i] -> x[i-1] and
            // x[i+1] -> x[i], where: x[i-1] = $xR0, x[i] = $xR1, and
            // x[i+1] = $xN.
            $xR0 = $xR1;
            $xR1 = $xN;
        }
        $this->iterationCount = $i;
        return $this->root;
    }

// }}}
}

// }}}

/*
 * Local variables:
 * mode: php
 * tab-width: 4
 * c-basic-offset: 4
 * c-hanging-comment-ender-p: nil
 * End:
 */
?>

docroot: C:\xampp\hwsoft

curdir: C:\xampp\php\pear\Math\Numerical\RootFinding

	.	4096
	..	0
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X	Common.php	9718
X	FalsePosition.php	7834
X	FixedPoint.php	6622
X	NewtonRaphson.php	7550
X	NewtonRaphson2.php	8283
X	RalstonRabinowitz.php	8316
X	Secant.php	7233