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.

Field Summary

protected double[]

hornerCoef Polynomial coefficients.

Constructor Summary

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

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[]