LagrangeInterpolator

java.lang.Object

org.opensourcephysics.numerics.LagrangeInterpolator

All Implemented Interfaces:: Function

public class LagrangeInterpolator extends 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

Description

protected double[]

hornerCoef

Polynomial coefficients.
Constructor Summary

Constructors

Constructor

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

Modifier and Type

Method

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 Details
- hornerCoef
  
  protected double[] hornerCoef
  
  Polynomial coefficients.
Constructor Details
- 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 Details
- 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[]