org.spaceroots.mantissa.functions.scalar
Class ComputableFunctionSampler

java.lang.Object
  org.spaceroots.mantissa.functions.scalar.ComputableFunctionSampler

All Implemented Interfaces:

SampledFunction, Serializable

public class ComputableFunctionSampler

extends Object

implements SampledFunction, Serializable

This class is a wrapper allowing to sample a ComputableFunction.

The sample produced is a regular sample. It can be specified by several means :

• from an initial point a step and a number of points
• from a range and a number of points
• from a range and a step between points.

In the latter case, the step can optionaly be adjusted in order to have the last point exactly at the upper bound of the range.

The sample points are computed on demand, they are not stored. This allow to use this method for very large sample with little memory overhead. The drawback is that if the same sample points are going to be requested several times, they will be recomputed each time. In this case, the user should consider storing the points by some other means.

Version:

$Id: ComputableFunctionSampler.java 1666 2005-12-15 16:37:55Z luc $

Author:

L. Maisonobe

See Also:

ComputableFunction, Serialized Form

Constructor Summary

ComputableFunctionSampler(ComputableFunction function, double[] range, double step, boolean adjustStep)
Constructor.

ComputableFunctionSampler(ComputableFunction function, double[] range, int n)
Constructor.

ComputableFunctionSampler(ComputableFunction function, double begin, double step, int n)
Constructor.

Method Summary

ScalarValuedPair	samplePointAt(int index) Get the abscissa and value of the sample at the specified index.
int	size() Get the number of points in the sample.

Methods inherited from class java.lang.Object

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

Constructor Detail

ComputableFunctionSampler

public ComputableFunctionSampler(ComputableFunction function,
                                 double begin,
                                 double step,
                                 int n)

Constructor. Build a sample from an ComputableFunction. Beware of the classical off-by-one problem ! If you want to have a sample like this : 0.0, 0.1, 0.2 ..., 1.0, then you should specify step = 0.1 and n = 11 (not n = 10).

Parameters:

begin - beginning of the range (will be the abscissa of the first point)

step - step between points

n - number of points

ComputableFunctionSampler

public ComputableFunctionSampler(ComputableFunction function,
                                 double[] range,
                                 int n)

Constructor. Build a sample from an ComputableFunction.

Parameters:

range - abscissa range (from range [0] to range [1])

n - number of points

ComputableFunctionSampler

public ComputableFunctionSampler(ComputableFunction function,
                                 double[] range,
                                 double step,
                                 boolean adjustStep)

Constructor. Build a sample from an ComputableFunction.

Parameters:

range - abscissa range (from range [0] to range [1])

step - step between points

adjustStep - if true, the step is reduced in order to have the last point of the sample exactly at range [1], if false the last point will be between range [1] - step and range [1]

Method Detail

size

public int size()

Description copied from interface: SampledFunction

Get the number of points in the sample.

Specified by:

size in interface SampledFunction

Returns:

number of points in the sample

samplePointAt

public ScalarValuedPair samplePointAt(int index)
                               throws ArrayIndexOutOfBoundsException,
                                      FunctionException

Description copied from interface: SampledFunction

Get the abscissa and value of the sample at the specified index.

Specified by:

samplePointAt in interface SampledFunction

Parameters:

index - index in the sample, should be between 0 and SampledFunction.size() - 1

Returns:

abscissa and value of the sample at the specified index

Throws:

ArrayIndexOutOfBoundsException - if the index is wrong

FunctionException - if an eventual underlying function throws one