vec_math
Class SimpleIntegrator

java.lang.Object
  vec_math.SimpleIntegrator

All Implemented Interfaces:

Integrator

public class SimpleIntegrator
extends Object
implements Integrator

The simpliest Integrator possible. Implements a trapezoid-integrator. Only the accumulated sum is stored. Highly inefficient if used with setting of huge data sets.

Note that it is within the user's responsibility to correctly initialize the numerical integrator with a call to initData(double, double) prior to calling the one of the add(double, double) methods.

Nested Class Summary

static class	SimpleIntegrator.E Tests the integrator.
static class	SimpleIntegrator.Gauss Tests the integrator.
static class	SimpleIntegrator.Xsquare Tests the integrator.

Field Summary

private double	xprior The x-value prior-to-last.
private double	yprior The y-value prior-to-last.
private double	ysum The accumulated sum, i.e.

Constructor Summary

SimpleIntegrator()

Method Summary

void	add(double y) Adds a new y-data point with a step-size of one.
void	add(double x, double y) Adds a new x/y data point.
private void	addTrapezoid(double base, double ynew) This private method calculates the area of an trapezoid and adds it to the accumulated sum in ysum.
double	getIntegral() Calculates the difference at the last points added.
double	getIntegral(double x) Cannot compute.
void	initData(double xstart, double ystart) Initializes the integrator.
void	setData(double[] y) Takes the last two y-values as the last and prior-to-last y value.
void	setData(double[] x, double[] y) Lengthy implementation erasing all old data and step-by-step adding the new one.

Methods inherited from class java.lang.Object

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

Field Detail

xprior

private double xprior

The x-value prior-to-last.

yprior

private double yprior

The y-value prior-to-last.

ysum

private double ysum

The accumulated sum, i.e. the integral.

Constructor Detail

SimpleIntegrator

public SimpleIntegrator()

Method Detail

initData

public void initData(double xstart,
                     double ystart)

Initializes the integrator. Here, it sets the two x/y prior-data, i.e. xprior and yprior. Additionally, the accumulated sum is set to zero.

Specified by:

initData in interface Integrator

add

public void add(double x,
                double y)

Adds a new x/y data point. Uses the xprior value to calculate a step-size and then calls addTrapezoid(double, double).

Specified by:

add in interface Integrator

Parameters:

x - A newly added x-value.

y - A newly added y-value.

add

public void add(double y)

Adds a new y-data point with a step-size of one.

Specified by:

add in interface Integrator

Parameters:

y - A newly added y-value.

addTrapezoid

private void addTrapezoid(double base,
                          double ynew)

This private method calculates the area of an trapezoid and adds it to the accumulated sum in ysum. Additionally, the y-prior value is updated to the new y value.

setData

public void setData(double[] x,
                    double[] y)

Lengthy implementation erasing all old data and step-by-step adding the new one. Calls initData(double, double) with the first x/y pair and then continuously adds new data with the add(double, double) method.

Specified by:

setData in interface Integrator

Parameters:

x - A double-array representing the x-axis values.

y - A double-array representing the y-axis values.

setData

public void setData(double[] y)

Takes the last two y-values as the last and prior-to-last y value.

Specified by:

setData in interface Integrator

Parameters:

y - A double-array representing the y-axis values.

getIntegral

public double getIntegral()

Calculates the difference at the last points added. If the equal- stepped version is used, the step size is calculated from the default setting done in the construction phase. Note that deliberate missuse (i.e. calling add with x/y, then adding only y values) can yield wrong results.

Specified by:

getIntegral in interface Integrator

Returns:

The difference of the y-values devided by the stepsize in x.

getIntegral

public double getIntegral(double x)

Cannot compute.

Specified by:

getIntegral in interface Integrator