## Class GaussIntegrator

• java.lang.Object
• org.apache.commons.math4.legacy.analysis.integration.gauss.GaussIntegrator
• Direct Known Subclasses:
SymmetricGaussIntegrator

public class GaussIntegrator
extends Object
Class that implements the Gaussian rule for integrating a weighted function.
Since:
3.1
• ### Constructor Summary

Constructors
Constructor Description
GaussIntegrator​(double[] points, double[] weights)
Creates an integrator from the given points and weights.
GaussIntegrator​(Pair<double[],​double[]> pointsAndWeights)
Creates an integrator from the given pair of points (first element of the pair) and weights (second element of the pair.
• ### Method Summary

All Methods
Modifier and Type Method Description
int getNumberOfPoints()
double getPoint​(int index)
Gets the integration point at the given index.
double getWeight​(int index)
Gets the weight of the integration point at the given index.
double integrate​(UnivariateFunction f)
Returns an estimate of the integral of f(x) * w(x), where w is a weight function that depends on the actual flavor of the Gauss integration scheme.
• ### Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
• ### Constructor Detail

• #### GaussIntegrator

public GaussIntegrator​(double[] points,
double[] weights)
Creates an integrator from the given points and weights. The integration interval is defined by the first and last value of points which must be sorted in increasing order.
Parameters:
points - Integration points.
weights - Weights of the corresponding integration nodes.
Throws:
NonMonotonicSequenceException - if the points are not sorted in increasing order.
DimensionMismatchException - if points and weights don't have the same length
• #### GaussIntegrator

public GaussIntegrator​(Pair<double[],​double[]> pointsAndWeights)
Creates an integrator from the given pair of points (first element of the pair) and weights (second element of the pair.
Parameters:
pointsAndWeights - Integration points and corresponding weights.
Throws:
NonMonotonicSequenceException - if the points are not sorted in increasing order.
GaussIntegrator(double[], double[])
• ### Method Detail

• #### integrate

public double integrate​(UnivariateFunction f)
Returns an estimate of the integral of f(x) * w(x), where w is a weight function that depends on the actual flavor of the Gauss integration scheme. The algorithm uses the points and associated weights, as passed to the constructor.
Parameters:
f - Function to integrate.
Returns:
the integral of the weighted function.
• #### getNumberOfPoints

public int getNumberOfPoints()
Returns:
the order of the integration rule (the number of integration points).
• #### getPoint

public double getPoint​(int index)
Gets the integration point at the given index. The index must be in the valid range but no check is performed.
Parameters:
index - index of the integration point
Returns:
the integration point.
• #### getWeight

public double getWeight​(int index)
Gets the weight of the integration point at the given index. The index must be in the valid range but no check is performed.
Parameters:
index - index of the integration point
Returns:
the weight.