## org.apache.commons.math3.analysis.integration.gauss
Class GaussIntegrator

    java.lang.Object
      org.apache.commons.math3.analysis.integration.gauss.GaussIntegrator

    public class GaussIntegrator

extends java.lang.Object

Class that implements the Gaussian rule for `integrating` a weighted function.

Since:
  3.1
Version:
  $Id: GaussIntegrator.java 1382197 2012-09-07 22:35:01Z erans $

Field Summary
`private double[]` `points` Nodes.
`private double[]` `weights` Nodes weights.

Constructor Summary
`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
`int` `getNumberOfPoints()`
`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`

Field Detail

### points

    private final double[] points

  Nodes.

### weights

    private final double[] weights

  Nodes weights.

Constructor Detail

### GaussIntegrator

    public GaussIntegrator(double[] points,
                           double[] weights)
                    throws NonMonotonicSequenceException

  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.

### GaussIntegrator

    public GaussIntegrator(Pair<double[],double[]> pointsAndWeights)
                    throws NonMonotonicSequenceException

  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.
  See Also:
    `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).

Copyright (c) 2003-2013 Apache Software Foundation