dwvisser.analysis
Class LevenbergMarquadt

java.lang.Object
  |
  +--dwvisser.analysis.LevenbergMarquadt

public class LevenbergMarquadt

extends java.lang.Object

This uses the Levenberg-Marquadt prescription for finding the local minimum of chi-squared given seed parameter values for the function to fit. The NonLinearFit class which creates and calls this must supply the function evaluation and differentiation.

Version:

0.5, 8/28/98

Author:

Dale Visser

See Also:

NonLinearFit, GaussianFit

Field Summary

static int	FIRST_ITERATION int used when calling to calculate the first iteration
static int	LAST_ITERATION int used when calling to calculate the last iteration
static int	NEXT_ITERATION int used when calling to calculate subsequent iterations

Constructor Summary

LevenbergMarquadt(NonLinearFit nlf)
Class constructor giving handle to parent.

Method Summary

double	getChiSq() Gives the chi-sqared value of the latest iteration.
int	getDegreesOfFreedom()
void	iterate(int iteration) Calculates a single iteration of the minimization routine.
void	setup(double[] counts, double[] errors, int minChannel, int maxChannel) Sets the histogram values and the boundaries for the fit.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

FIRST_ITERATION

public static final int FIRST_ITERATION

int used when calling to calculate the first iteration

See Also:

Constant Field Values

NEXT_ITERATION

public static final int NEXT_ITERATION

int used when calling to calculate subsequent iterations

See Also:

Constant Field Values

LAST_ITERATION

public static final int LAST_ITERATION

int used when calling to calculate the last iteration

See Also:

Constant Field Values

Constructor Detail

LevenbergMarquadt

public LevenbergMarquadt(NonLinearFit nlf)

Class constructor giving handle to parent.

Parameters:

nlf - the parent NonLinearFit object creating this

Method Detail

setup

public void setup(double[] counts,
                  double[] errors,
                  int minChannel,
                  int maxChannel)

Sets the histogram values and the boundaries for the fit.

Parameters:

counts - the counts in the histogram to fit

minChannel - the lower limit of the fit

maxChannel - the upper limit of the fit

iterate

public void iterate(int iteration)
             throws java.lang.Exception

Calculates a single iteration of the minimization routine.

Parameters:

iteration - indicates first, middle, or final iteration

Throws:

java.lang.Exception - trying to diagonalize singular matrices

See Also:

FIRST_ITERATION, NEXT_ITERATION, LAST_ITERATION, NonLinearFit.doFit()

getChiSq

public double getChiSq()

Gives the chi-sqared value of the latest iteration.

Returns:

chiSq/dof

getDegreesOfFreedom

public int getDegreesOfFreedom()