org.apache.commons.math.analysis
Class TrapezoidIntegrator

java.lang.Object
  org.apache.commons.math.analysis.UnivariateRealIntegratorImpl
      org.apache.commons.math.analysis.TrapezoidIntegrator

All Implemented Interfaces:

java.io.Serializable, UnivariateRealIntegrator

public class TrapezoidIntegrator
extends UnivariateRealIntegratorImpl

Implements the Trapezoidal Rule for integration of real univariate functions. For reference, see Introduction to Numerical Analysis, ISBN 038795452X, chapter 3.

The function should be integrable.

Since:

1.2

Version:

$Revision: 620312 $ $Date: 2008-02-10 12:28:59 -0700 (Sun, 10 Feb 2008) $

See Also:

Serialized Form

Field Summary

private double	s intermediate result
private static long	serialVersionUID serializable version identifier

Fields inherited from class org.apache.commons.math.analysis.UnivariateRealIntegratorImpl

defaultMaximalIterationCount, defaultMinimalIterationCount, defaultRelativeAccuracy, f, iterationCount, maximalIterationCount, minimalIterationCount, relativeAccuracy, result, resultComputed

Constructor Summary

TrapezoidIntegrator(UnivariateRealFunction f)
Construct an integrator for the given function.

Method Summary

double	integrate(double min, double max) Integrate the function in the given interval.
(package private) double	stage(double min, double max, int n) Compute the n-th stage integral of trapezoid rule.
protected void	verifyIterationCount() Verifies that the iteration limits are valid and within the range.

Methods inherited from class org.apache.commons.math.analysis.UnivariateRealIntegratorImpl

clearResult, getIterationCount, getMaximalIterationCount, getMinimalIterationCount, getRelativeAccuracy, getResult, isSequence, resetMaximalIterationCount, resetMinimalIterationCount, resetRelativeAccuracy, setMaximalIterationCount, setMinimalIterationCount, setRelativeAccuracy, setResult, verifyInterval

Methods inherited from class java.lang.Object

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

Field Detail

serialVersionUID

private static final long serialVersionUID

serializable version identifier

See Also:

Constant Field Values

s

private double s

intermediate result

Constructor Detail

TrapezoidIntegrator

public TrapezoidIntegrator(UnivariateRealFunction f)

Construct an integrator for the given function.

Parameters:

f - function to integrate

Method Detail

stage

double stage(double min,
             double max,
             int n)
       throws FunctionEvaluationException

Compute the n-th stage integral of trapezoid rule. This function should only be called by API integrate() in the package. To save time it does not verify arguments - caller does.

The interval is divided equally into 2^n sections rather than an arbitrary m sections because this configuration can best utilize the alrealy computed values.

Parameters:

min - the lower bound for the interval

max - the upper bound for the interval

n - the stage of 1/2 refinement, n = 0 is no refinement

Returns:

the value of n-th stage integral

Throws:

FunctionEvaluationException - if an error occurs evaluating the function

integrate

public double integrate(double min,
                        double max)
                 throws MaxIterationsExceededException,
                        FunctionEvaluationException,
                        java.lang.IllegalArgumentException

Integrate the function in the given interval.

Parameters:

min - the lower bound for the interval

max - the upper bound for the interval

Returns:

the value of integral

Throws:

MaxIterationsExceededException - if the maximum iteration count is exceeded or the integrator detects convergence problems otherwise

FunctionEvaluationException - if an error occurs evaluating the function

java.lang.IllegalArgumentException - if any parameters are invalid

verifyIterationCount

protected void verifyIterationCount()
                             throws java.lang.IllegalArgumentException

Verifies that the iteration limits are valid and within the range.

Overrides:

verifyIterationCount in class UnivariateRealIntegratorImpl

Throws:

java.lang.IllegalArgumentException - if not