org.opensourcephysics.numerics

Class LagrangeInterpolator

java.lang.Object

org.opensourcephysics.numerics.LagrangeInterpolator

All Implemented Interfaces:

Function

public class LagrangeInterpolator
extends java.lang.Object
implements Function

LagrangeInterpolator uses a polynomial interpolation formula to evaluate values between data points.

Version:

1.0

Author:

W. Christian

Field Summary

Fields

Modifier and Type	Field and Description
protected double[]	hornerCoef Polynomial coefficients.

Constructor Summary

Constructors

Constructor and Description
LagrangeInterpolator(double[] xdata, double[] ydata) Constructs a Lagrange interpolating polynomial from the given data using Horner's expansion for the representation of the polynomial.

Method Summary

Methods

Modifier and Type	Method and Description
double	evaluate(double x) Computes the interpolated y value for a given x value.
double[]	getCoefficients() Gets the polynomial coefficients c in c[0] + c[1] * x + c[2] * x^2 + ....

Methods inherited from class java.lang.Object

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

Field Detail

hornerCoef

protected double[] hornerCoef

Polynomial coefficients.

Constructor Detail

LagrangeInterpolator

public LagrangeInterpolator(double[] xdata,
                    double[] ydata)

Constructs a Lagrange interpolating polynomial from the given data using Horner's expansion for the representation of the polynomial.

Parameters:

xdata - double[]

ydata - double[]

Method Detail

evaluate

public double evaluate(double x)

Computes the interpolated y value for a given x value.

Specified by:

evaluate in interface Function

Parameters:

x - value

Returns:

interpolated y value

getCoefficients

public double[] getCoefficients()

Gets the polynomial coefficients c in c[0] + c[1] * x + c[2] * x^2 + .... This routine should be used with care because the Vandermonde matrix that is being solved is ill conditioned. See Press et al.

Returns:

double[]