java.lang.Object
- org.apache.commons.math.transform.FastCosineTransformer

All Implemented Interfaces:

RealTransformer
```
public class FastCosineTransformer
extends java.lang.Object
implements RealTransformer
```
Implements the Fast Cosine Transform for transformation of one-dimensional data sets. For reference, see Fast Fourier Transforms, ISBN 0849371635, chapter 3.
FCT is its own inverse, up to a multiplier depending on conventions. The equations are listed in the comments of the corresponding methods.

Different from FFT and FST, FCT requires the length of data set to be power of 2 plus one. Users should especially pay attention to the function transformation on how this affects the sampling.

As of version 2.0 this no longer implements Serializable

Since:

1.2

Version:

$Revision:670469 $ $Date:2008-06-23 10:01:38 +0200 (lun., 23 juin 2008) $

Constructor Summary

Constructors
Constructor Description

FastCosineTransformer()
Construct a default transformer.

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`protected double[]`	`fct(double[] f)`	Perform the FCT algorithm (including inverse).
`double[]`	`inversetransform(double[] f)`	Inversely transform the given real data set.
`double[]`	`inversetransform(UnivariateRealFunction f, double min, double max, int n)`	Inversely transform the given real function, sampled on the given interval.
`double[]`	`inversetransform2(double[] f)`	Inversely transform the given real data set.
`double[]`	`inversetransform2(UnivariateRealFunction f, double min, double max, int n)`	Inversely transform the given real function, sampled on the given interval.
`double[]`	`transform(double[] f)`	Transform the given real data set.
`double[]`	`transform(UnivariateRealFunction f, double min, double max, int n)`	Transform the given real function, sampled on the given interval.
`double[]`	`transform2(double[] f)`	Transform the given real data set.
`double[]`	`transform2(UnivariateRealFunction f, double min, double max, int n)`	Transform the given real function, sampled on the given interval.

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

- Constructor Detail
  - FastCosineTransformer
```
public FastCosineTransformer()
```
    Construct a default transformer.
- Method Detail
  - transform
```
public double[] transform(double[] f)
                   throws java.lang.IllegalArgumentException
```
    Transform the given real data set.
    The formula is F_n = (1/2) [f₀ + (-1)ⁿ f_N] + ∑_k=1^N-1 f_k cos(π nk/N)
    
    Specified by:
    
    transform in interface RealTransformer
    
    Parameters:
    
    f - the real data array to be transformed
    
    Returns:
    
    the real transformed array
    
    Throws:
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - transform
```
public double[] transform(UnivariateRealFunction f,
                          double min,
                          double max,
                          int n)
                   throws FunctionEvaluationException,
                          java.lang.IllegalArgumentException
```
    Transform the given real function, sampled on the given interval.
    The formula is F_n = (1/2) [f₀ + (-1)ⁿ f_N] + ∑_k=1^N-1 f_k cos(π nk/N)
    
    Specified by:
    
    transform in interface RealTransformer
    
    Parameters:
    
    f - the function to be sampled and transformed
    
    min - the lower bound for the interval
    
    max - the upper bound for the interval
    
    n - the number of sample points
    
    Returns:
    
    the real transformed array
    
    Throws:
    
    FunctionEvaluationException - if function cannot be evaluated at some point
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - transform2
```
public double[] transform2(double[] f)
                    throws java.lang.IllegalArgumentException
```
    Transform the given real data set.
    The formula is F_n = √(1/2N) [f₀ + (-1)ⁿ f_N] + √(2/N) ∑_k=1^N-1 f_k cos(π nk/N)
    
    Parameters:
    
    f - the real data array to be transformed
    
    Returns:
    
    the real transformed array
    
    Throws:
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - transform2
```
public double[] transform2(UnivariateRealFunction f,
                           double min,
                           double max,
                           int n)
                    throws FunctionEvaluationException,
                           java.lang.IllegalArgumentException
```
    Transform the given real function, sampled on the given interval.
    The formula is F_n = √(1/2N) [f₀ + (-1)ⁿ f_N] + √(2/N) ∑_k=1^N-1 f_k cos(π nk/N)
    
    Parameters:
    
    f - the function to be sampled and transformed
    
    min - the lower bound for the interval
    
    max - the upper bound for the interval
    
    n - the number of sample points
    
    Returns:
    
    the real transformed array
    
    Throws:
    
    FunctionEvaluationException - if function cannot be evaluated at some point
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - inversetransform
```
public double[] inversetransform(double[] f)
                          throws java.lang.IllegalArgumentException
```
    Inversely transform the given real data set.
    The formula is f_k = (1/N) [F₀ + (-1)^k F_N] + (2/N) ∑_n=1^N-1 F_n cos(π nk/N)
    
    Specified by:
    
    inversetransform in interface RealTransformer
    
    Parameters:
    
    f - the real data array to be inversely transformed
    
    Returns:
    
    the real inversely transformed array
    
    Throws:
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - inversetransform
```
public double[] inversetransform(UnivariateRealFunction f,
                                 double min,
                                 double max,
                                 int n)
                          throws FunctionEvaluationException,
                                 java.lang.IllegalArgumentException
```
    Inversely transform the given real function, sampled on the given interval.
    The formula is f_k = (1/N) [F₀ + (-1)^k F_N] + (2/N) ∑_n=1^N-1 F_n cos(π nk/N)
    
    Specified by:
    
    inversetransform in interface RealTransformer
    
    Parameters:
    
    f - the function to be sampled and inversely transformed
    
    min - the lower bound for the interval
    
    max - the upper bound for the interval
    
    n - the number of sample points
    
    Returns:
    
    the real inversely transformed array
    
    Throws:
    
    FunctionEvaluationException - if function cannot be evaluated at some point
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - inversetransform2
```
public double[] inversetransform2(double[] f)
                           throws java.lang.IllegalArgumentException
```
    Inversely transform the given real data set.
    The formula is f_k = √(1/2N) [F₀ + (-1)^k F_N] + √(2/N) ∑_n=1^N-1 F_n cos(π nk/N)
    
    Parameters:
    
    f - the real data array to be inversely transformed
    
    Returns:
    
    the real inversely transformed array
    
    Throws:
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - inversetransform2
```
public double[] inversetransform2(UnivariateRealFunction f,
                                  double min,
                                  double max,
                                  int n)
                           throws FunctionEvaluationException,
                                  java.lang.IllegalArgumentException
```
    Inversely transform the given real function, sampled on the given interval.
    The formula is f_k = √(1/2N) [F₀ + (-1)^k F_N] + √(2/N) ∑_n=1^N-1 F_n cos(π nk/N)
    
    Parameters:
    
    f - the function to be sampled and inversely transformed
    
    min - the lower bound for the interval
    
    max - the upper bound for the interval
    
    n - the number of sample points
    
    Returns:
    
    the real inversely transformed array
    
    Throws:
    
    FunctionEvaluationException - if function cannot be evaluated at some point
    
    java.lang.IllegalArgumentException - if any parameters are invalid
  - fct
```
protected double[] fct(double[] f)
                throws java.lang.IllegalArgumentException
```
    Perform the FCT algorithm (including inverse).
    
    Parameters:
    
    f - the real data array to be transformed
    
    Returns:
    
    the real transformed array
    
    Throws:
    
    java.lang.IllegalArgumentException - if any parameters are invalid

Class FastCosineTransformer

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

FastCosineTransformer

Method Detail

transform

transform

transform2

transform2

inversetransform

inversetransform

inversetransform2

inversetransform2

fct