Package org.apache.commons.math4.legacy.analysis.interpolation

Class DividedDifferenceInterpolator

java.lang.Object

org.apache.commons.math4.legacy.analysis.interpolation.DividedDifferenceInterpolator

All Implemented Interfaces:

UnivariateInterpolator

public class DividedDifferenceInterpolator
extends Object
implements UnivariateInterpolator

Implements the Divided Difference Algorithm for interpolation of real univariate functions. For reference, see Introduction to Numerical Analysis, ISBN 038795452X, chapter 2.

The actual code of Neville's evaluation is in PolynomialFunctionLagrangeForm, this class provides an easy-to-use interface to it.

Since:

1.2

Constructor Summary

Constructors

Constructor	Description
DividedDifferenceInterpolator()

Method Summary

Modifier and Type	Method	Description
protected static double[]	computeDividedDifference(double[] x, double[] y)	Return a copy of the divided difference array.
PolynomialFunctionNewtonForm	interpolate(double[] x, double[] y)	Compute an interpolating function for the dataset.

Methods inherited from class java.lang.Object

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

Constructor Detail

DividedDifferenceInterpolator

public DividedDifferenceInterpolator()

Method Detail

interpolate

public PolynomialFunctionNewtonForm interpolate(double[] x,
                                                double[] y)
                                         throws DimensionMismatchException,
                                                NumberIsTooSmallException,
                                                NonMonotonicSequenceException

Compute an interpolating function for the dataset.

Specified by:

interpolate in interface UnivariateInterpolator

Parameters:

x - Interpolating points array.

y - Interpolating values array.

Returns:

a function which interpolates the dataset.

Throws:

DimensionMismatchException - if the array lengths are different.

NumberIsTooSmallException - if the number of points is less than 2.

NonMonotonicSequenceException - if x is not sorted in strictly increasing order.

computeDividedDifference

protected static double[] computeDividedDifference(double[] x,
                                                   double[] y)
                                            throws DimensionMismatchException,
                                                   NumberIsTooSmallException,
                                                   NonMonotonicSequenceException

Return a copy of the divided difference array.

The divided difference array is defined recursively by

 f[x0] = f(x0)
 f[x0,x1,...,xk] = (f[x1,...,xk] - f[x0,...,x[k-1]]) / (xk - x0)
 

The computational complexity is \(O(n^2)\) where \(n\) is the common length of x and y.

Parameters:

x - Interpolating points array.

y - Interpolating values array.

Returns:

a fresh copy of the divided difference array.

Throws:

DimensionMismatchException - if the array lengths are different.

NumberIsTooSmallException - if the number of points is less than 2.

NonMonotonicSequenceException - if x is not sorted in strictly increasing order.