uk.ac.starlink.diva.interp

Class AkimaSplineInterp

java.lang.Object

uk.ac.starlink.diva.interp.AbstractInterpolator

uk.ac.starlink.diva.interp.LinearInterp

uk.ac.starlink.diva.interp.AkimaSplineInterp

All Implemented Interfaces:

Interpolator

public class AkimaSplineInterp
extends LinearInterp

Interpolate a series of points using a scheme based Akima's splines.

The effect is supposed to construct reasonable analytic curves through discrete data points (i.e. like those a human would produce).

Version:

$Id$

Author:

Peter W. Draper

Field Summary

Fields inherited from class uk.ac.starlink.diva.interp.AbstractInterpolator

c, decr, x, y

Constructor Summary

Constructors

Constructor and Description
AkimaSplineInterp() Create an instance with no coordinates.
AkimaSplineInterp(double[] x, double[] y) Create an instance with the given coordinates.

Method Summary

Modifier and Type	Method and Description
double	interpolate(double xp) Return the interpolated value corresponding to some arbitrary X coordinate.
static void	main(String[] args) Simple test entry point
void	setCoords(double[] x, double[] y, boolean check) Set or reset the coordinates used by this interpolator.

Methods inherited from class uk.ac.starlink.diva.interp.LinearInterp

guessStep

Methods inherited from class uk.ac.starlink.diva.interp.AbstractInterpolator

appendValue, binarySearch, evalYData, evalYDataArray, getCount, getXCoord, getXCoords, getYCoord, getYCoords, isFull, isIncreasing, stepGuess

Methods inherited from class java.lang.Object

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

Constructor Detail

AkimaSplineInterp

public AkimaSplineInterp()

Create an instance with no coordinates. A call to setCoords must be made before any other methods.

AkimaSplineInterp

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

Create an instance with the given coordinates. Interpolation is by X coordinate see the interpolate method. The X coordinates should be monotonic, either increasing or decreasing. Same value X coordinates are not allowed.

Parameters:

x - the X coordinates.

y - the Y coordinates.

Method Detail

setCoords

public void setCoords(double[] x,
                      double[] y,
                      boolean check)

Description copied from interface: Interpolator

Set or reset the coordinates used by this interpolator.

Specified by:

setCoords in interface Interpolator

Overrides:

setCoords in class AbstractInterpolator

Parameters:

x - the X coordinates.

y - the Y coordinates.

check - whether to check the monotonic direction (compares 0 and 1 values of x). Use this when you need to preserve the direction temporarily even though the order may currently be switched, but take care to reorder before interpolating.

interpolate

public double interpolate(double xp)

Description copied from interface: Interpolator

Return the interpolated value corresponding to some arbitrary X coordinate.

Specified by:

interpolate in interface Interpolator

Overrides:

interpolate in class LinearInterp

Parameters:

xp - the X coordinate at which an interpolated Y coordinate is required.

Returns:

the interpolated value.

main

public static void main(String[] args)

Simple test entry point