FastHadamardTransform (Apache Commons Math 4.0-SNAPSHOT)

java.lang.Object
- org.apache.commons.math4.transform.FastHadamardTransform

All Implemented Interfaces:

Function<double[],double[]>, UnaryOperator<double[]>, RealTransform
```
public class FastHadamardTransform
extends Object
implements RealTransform
```
Fast Hadamard Transform (FHT).
The FHT can also transform integer vectors into integer vectors. However, this transform cannot be inverted directly, due to a scaling factor that may lead to rational results (for example, the inverse transform of integer vector (0, 1, 0, 1) is vector (1/2, -1/2, 0, 0).

Constructor Summary

Constructors
Constructor Description

FastHadamardTransform()
Default constructor.

FastHadamardTransform(boolean inverse)

Method Summary

All Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`double[]`	`apply(double[] f)`	Returns the transform of the specified data set.
`int[]`	`apply(int[] f)`	Returns the forward transform of the given data set.

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

Methods inherited from interface java.util.function.Function
andThen, compose

Methods inherited from interface org.apache.commons.math4.transform.RealTransform
apply

- Constructor Detail
  - FastHadamardTransform
```
public FastHadamardTransform()
```
    Default constructor.
  - FastHadamardTransform
```
public FastHadamardTransform(boolean inverse)
```
    Parameters:
    
    inverse - Whether to perform the inverse transform.
- Method Detail
  - apply
```
public double[] apply(double[] f)
```
    Returns the transform of the specified data set.
    
    Specified by:
    
    apply in interface Function<double[],double[]>
    
    Specified by:
    
    apply in interface RealTransform
    
    Parameters:
    
    f - the data array to be transformed (signal).
    
    Returns:
    
    the transformed array (spectrum).
    
    Throws:
    
    IllegalArgumentException - if the length of the data array is not a power of two.
  - apply
```
public int[] apply(int[] f)
```
    Returns the forward transform of the given data set. The integer transform cannot be inverted directly, due to a scaling factor which may lead to double results.
    
    Parameters:
    
    f - Data array to be transformed (signal).
    
    Returns:
    
    the transformed array (spectrum).
    
    Throws:
    
    IllegalArgumentException - if the length of the data array is not a power of two.