AbstractInterpolator (Starlink-UK API)

java.lang.Object
- uk.ac.starlink.diva.interp.AbstractInterpolator

All Implemented Interfaces:

Interpolator

Direct Known Subclasses:

LinearInterp
```
public abstract class AbstractInterpolator
extends Object
implements Interpolator
```
Abstract base class for all Interpolators. Interpolation assumes a monotonic set of X coordinates (the ordinates) and an arbitrary set of Y coordinates (the data values). Interpolation of the Y coordinates is provided by the specification of any possible X coordinate or array of X coordinates.
Extenders of this class need to at implement the interpolate(double), and probably a few others.

Version:

$Id$

Author:

Peter W. Draper

Field Summary

Fields
Modifier and Type	Field and Description
`protected double[]`	`c` Some coefficients, if any associated with the fit.
`protected boolean`	`decr` Whether the X coordinates are monotonically decreasing.
`protected double[]`	`x` The X coordinates.
`protected double[]`	`y` The Y coordinates.

Constructor Summary

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

Method Summary

All Methods Instance Methods Abstract Methods Concrete Methods
Modifier and Type	Method and Description
`void`	`appendValue(double newx, double newy)` Append a new position to the existing coordinates.
`protected int[]`	`binarySearch(double[] array, double value)` Return two indices of the values in an array that lie above and below a given value.
`double`	`evalYData(double xp)` Return the interpolated value corresponding to some arbitrary X coordinate.
`double[]`	`evalYDataArray(double[] xps)` Return an array of interpolated value corresponding to some array of arbitrary X coordinates.
`int`	`getCount()` Get the number of coordinate positions that are being used by this interpolator.
`double`	`getXCoord(int index)` Get an X coordinate by index.
`double[]`	`getXCoords()` Get the X coordinates.
`double`	`getYCoord(int index)` Get a Y coordinate by index.
`double[]`	`getYCoords()` Get the Y coordinates.
`abstract double`	`interpolate(double xp)` Return the interpolated value corresponding to some arbitrary X coordinate.
`boolean`	`isFull()` Return if the Interpolator is full.
`boolean`	`isIncreasing()` Return the direction being used by this interpolator.
`void`	`setCoords(double[] x, double[] y, boolean check)` Set or reset the coordinates used by this interpolator.
`int`	`stepGuess()` A guess at the number of steps needed between the actual X coordinates that may be used to draw a reasonable representation of the curve being interpolated.

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Field Detail
  - x
```
protected double[] x
```
    The X coordinates. Must be monotonic. These form the basis for interpolation of the Y coordinates.
  - y
```
protected double[] y
```
    The Y coordinates. There should be at least as many of these values as X coordinates.
  - c
```
protected double[] c
```
    Some coefficients, if any associated with the fit.
  - decr
```
protected boolean decr
```
    Whether the X coordinates are monotonically decreasing.
- Constructor Detail
  - AbstractInterpolator
```
public AbstractInterpolator()
```
    Create an instance with no coordinates. A call to setCoords must be made before any other methods.
  - AbstractInterpolator
```
public AbstractInterpolator(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
  - stepGuess
```
public int stepGuess()
```
    Description copied from interface: Interpolator
    
    A guess at the number of steps needed between the actual X coordinates that may be used to draw a reasonable representation of the curve being interpolated.
    
    Specified by:
    
    stepGuess in interface Interpolator
  - 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
    
    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.
  - isIncreasing
```
public boolean isIncreasing()
```
    Description copied from interface: Interpolator
    
    Return the direction being used by this interpolator.
    
    Specified by:
    
    isIncreasing in interface Interpolator
  - appendValue
```
public void appendValue(double newx,
                        double newy)
```
    Description copied from interface: Interpolator
    
    Append a new position to the existing coordinates.
    
    Specified by:
    
    appendValue in interface Interpolator
  - getCount
```
public int getCount()
```
    Description copied from interface: Interpolator
    
    Get the number of coordinate positions that are being used by this interpolator.
    
    Specified by:
    
    getCount in interface Interpolator
    
    Returns:
    
    the number of positions that will be used.
  - isFull
```
public boolean isFull()
```
    Description copied from interface: Interpolator
    
    Return if the Interpolator is full. This may mean that the instance will ignore or refuse any further vectices.
    
    Specified by:
    
    isFull in interface Interpolator
  - getXCoords
```
public double[] getXCoords()
```
    Description copied from interface: Interpolator
    
    Get the X coordinates.
    
    Specified by:
    
    getXCoords in interface Interpolator
    
    Returns:
    
    the X coordinate array. Note this is not a copy, if you modify it you need to re-apply setCoords.
  - getXCoord
```
public double getXCoord(int index)
```
    Description copied from interface: Interpolator
    
    Get an X coordinate by index. If the index is invalid an out of bound exception will be thrown.
    
    Specified by:
    
    getXCoord in interface Interpolator
    
    Returns:
    
    the X coordinate.
  - getYCoords
```
public double[] getYCoords()
```
    Description copied from interface: Interpolator
    
    Get the Y coordinates.
    
    Specified by:
    
    getYCoords in interface Interpolator
    
    Returns:
    
    the Y coordinate array. Note this is not a copy, if you modify it you need to re-apply setCoords.
  - getYCoord
```
public double getYCoord(int index)
```
    Description copied from interface: Interpolator
    
    Get a Y coordinate by index. If the index is invalid an out of bound exception will be thrown.
    
    Specified by:
    
    getYCoord in interface Interpolator
    
    Returns:
    
    the Y coordinate.
  - interpolate
```
public abstract 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
    
    Parameters:
    
    xp - the X coordinate at which an interpolated Y coordinate is required.
    
    Returns:
    
    the interpolated value.
  - evalYData
```
public double evalYData(double xp)
```
    Description copied from interface: Interpolator
    
    Return the interpolated value corresponding to some arbitrary X coordinate.
    
    Specified by:
    
    evalYData in interface Interpolator
    
    Parameters:
    
    xp - the X coordinate at which an interpolated Y coordinate is required.
    
    Returns:
    
    the interpolated value.
  - evalYDataArray
```
public double[] evalYDataArray(double[] xps)
```
    Description copied from interface: Interpolator
    
    Return an array of interpolated value corresponding to some array of arbitrary X coordinates.
    
    Specified by:
    
    evalYDataArray in interface Interpolator
    
    Parameters:
    
    xps - the X coordinates at which interpolated Y coordinates are required.
    
    Returns:
    
    the interpolated values.
  - binarySearch
```
protected int[] binarySearch(double[] array,
                             double value)
```
    Return two indices of the values in an array that lie above and below a given value. If the value doesn't lie within the range the two indices are returned as the nearest end point. The array of values must be increasing or decreasing monotonically.
    
    Parameters:
    
    array - the array of values to be searched
    
    value - the value to be located

Class AbstractInterpolator

Field Summary

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Field Detail

x

y

c

decr

Constructor Detail

AbstractInterpolator

AbstractInterpolator

Method Detail

stepGuess

setCoords

isIncreasing

appendValue

getCount

isFull

getXCoords

getXCoord

getYCoords

getYCoord

interpolate

evalYData

evalYDataArray

binarySearch