Package ca.cgjennings.math

Class Interpolation.CubicSpline

java.lang.Object

ca.cgjennings.math.Interpolation.InterpolatedFunction

ca.cgjennings.math.Interpolation.CubicSpline

All Implemented Interfaces:

Fn

Enclosing class:

Interpolation

public static class Interpolation.CubicSpline
extends Interpolation.InterpolatedFunction

A CubicSpline interpolator passes through each point in its data set, connecting the points with cubic spline curves. The array of x values used to define the curve must be ordered and strictly increasing. That is, for i in 0..x.length-2, x[i] < x[i+1].

Field Summary

Fields inherited from interface ca.cgjennings.math.Fn

IDENTITY

Constructor Summary

Constructors

Constructor	Description
CubicSpline(double[] x, double[] y)	Creates a cubic spline that passes through the points (x[0],y[0]), (x[1],y[1]), ..., (x[x.length-1],y[y.length-1).
CubicSpline(double[] x, double[] y, double yp0, double ypN)	Creates a cubic spline that passes through the points (x[0],y[0]), (x[1],y[1]), ..., (x[x.length-1],y[y.length-1).

Method Summary

Modifier and Type	Method	Description
double	f(double xValue)	Returns the y-value of the interpolation function given an x-value.

Methods inherited from class ca.cgjennings.math.Interpolation.InterpolatedFunction

checkPoints

Methods inherited from class java.lang.Object

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

Constructor Detail

CubicSpline

public CubicSpline(double[] x,
                   double[] y)

Creates a cubic spline that passes through the points (x[0],y[0]), (x[1],y[1]), ..., (x[x.length-1],y[y.length-1). Default derivatives will be computed for the end points of the spline.

Parameters:

x - an array of x-values for the points

y - an array of y-values for the points

Throws:

java.lang.NullPointerException - if either array is null

java.lang.IllegalArgumentException - if the data point criteria are not met

CubicSpline

public CubicSpline(double[] x,
                   double[] y,
                   double yp0,
                   double ypN)

Creates a cubic spline that passes through the points (x[0],y[0]), (x[1],y[1]), ..., (x[x.length-1],y[y.length-1). This constructor specifies the derivatives at the lower (yp0) and upper (ypN) boundaries of the function.

Parameters:

x - an array of x-values for the points

y - an array of y-values for the points

yp0 - derivative at the lower boundary, or Double.NaN to let the interpolator choose

ypN - derivative at the upper boundary, or Double.NaN to let the interpolator choose

Throws:

java.lang.NullPointerException - if either array is null

java.lang.IllegalArgumentException - if the data point criteria are not met

Method Detail

f

public double f(double xValue)

Description copied from class: Interpolation.InterpolatedFunction

Returns the y-value of the interpolation function given an x-value.

Specified by:

f in interface Fn

Specified by:

f in class Interpolation.InterpolatedFunction

Parameters:

xValue - the value to evaluate the curve function at

Returns:

f(x), where f is a function for the interpolating curve