GeneralPurposeFFT_F64_1D (BoofCV Image Processing 0.16 API)

java.lang.Object
- boofcv.alg.transform.fft.GeneralPurposeFFT_F64_1D

```
public class GeneralPurposeFFT_F64_1D
extends Object
```
Computes 1D Discrete Fourier Transform (DFT) of complex and real, double precision data. The size of the data can be an arbitrary number. The code originally comes from General Purpose FFT Package written by Takuya Ooura (http://www.kurims.kyoto-u.ac.jp/~ooura/fft.html). See below for the full history.
This code has a bit of a history. Originally from General Purpose FFT. Which was then ported into JFFTPack written by Baoshe Zhang (http://jfftpack.sourceforge.net/), and then into JTransforms by Piotr Wendykier. The major modification from JTransforms is that the SMP code has been stripped out. It might be added back in once an SMP strategy has been finalized in BoofCV.
Code License: The original license of General Purpose FFT Package is shown below. This file will fall under the same license:
```
 Copyright Takuya OOURA, 1996-2001

 You may use, copy, modify and distribute this code for any purpose (include commercial use) and without fee.
 Please refer to this package when you modify this code.
 
```
Author:

Piotr Wendykier (piotr.wendykier@gmail.com), Peter Abeles

Constructor Summary

Constructors
Constructor and Description

GeneralPurposeFFT_F64_1D(int n)
Creates new instance of DoubleFFT_1D.

Constructors
Constructor and Description
`GeneralPurposeFFT_F64_1D(int n)` Creates new instance of DoubleFFT_1D.

Method Summary

Methods
Modifier and Type	Method and Description
`void`	`complexForward(double[] a)` Computes 1D forward DFT of complex data leaving the result in `a`.
`void`	`complexForward(double[] a, int offa)` Computes 1D forward DFT of complex data leaving the result in `a`.
`void`	`complexInverse(double[] a, boolean scale)` Computes 1D inverse DFT of complex data leaving the result in `a`.
`void`	`complexInverse(double[] a, int offa, boolean scale)` Computes 1D inverse DFT of complex data leaving the result in `a`.
`void`	`realForward(double[] a)` Computes 1D forward DFT of real data leaving the result in `a` .
`void`	`realForward(double[] a, int offa)` Computes 1D forward DFT of real data leaving the result in `a` .
`void`	`realForwardFull(double[] a)` Computes 1D forward DFT of real data leaving the result in `a` .
`void`	`realForwardFull(double[] a, int offa)` Computes 1D forward DFT of real data leaving the result in `a` .
`void`	`realInverse(double[] a, boolean scale)` Computes 1D inverse DFT of real data leaving the result in `a` .
`void`	`realInverse(double[] a, int offa, boolean scale)` Computes 1D inverse DFT of real data leaving the result in `a` .
`protected void`	`realInverse2(double[] a, int offa, boolean scale)`
`void`	`realInverseFull(double[] a, boolean scale)` Computes 1D inverse DFT of real data leaving the result in `a` .
`void`	`realInverseFull(double[] a, int offa, boolean scale)` Computes 1D inverse DFT of real data leaving the result in `a` .

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

- Constructor Detail
  - GeneralPurposeFFT_F64_1D
```
public GeneralPurposeFFT_F64_1D(int n)
```
    Creates new instance of DoubleFFT_1D.
    
    Parameters:
    n - size of data
- Method Detail
  - complexForward
```
public void complexForward(double[] a)
```
    Computes 1D forward DFT of complex data leaving the result in a. Complex number is stored as two double values in sequence: the real and imaginary part, i.e. the size of the input array must be greater or equal 2*n. The physical layout of the input data has to be as follows:
```
 a[2*k] = Re[k], 
 a[2*k+1] = Im[k], 0<=k<n
 
```
    Parameters:
    a - data to transform
  - complexForward
```
public void complexForward(double[] a,
                  int offa)
```
    Computes 1D forward DFT of complex data leaving the result in a. Complex number is stored as two double values in sequence: the real and imaginary part, i.e. the size of the input array must be greater or equal 2*n. The physical layout of the input data has to be as follows:
```
 a[offa+2*k] = Re[k], 
 a[offa+2*k+1] = Im[k], 0<=k<n
 
```
    Parameters:
    a - data to transform
    offa - index of the first element in array a
  - complexInverse
```
public void complexInverse(double[] a,
                  boolean scale)
```
    Computes 1D inverse DFT of complex data leaving the result in a. Complex number is stored as two double values in sequence: the real and imaginary part, i.e. the size of the input array must be greater or equal 2*n. The physical layout of the input data has to be as follows:
```
 a[2*k] = Re[k], 
 a[2*k+1] = Im[k], 0<=k<n
 
```
    Parameters:
    a - data to transform
    scale - if true then scaling is performed
  - complexInverse
```
public void complexInverse(double[] a,
                  int offa,
                  boolean scale)
```
    Computes 1D inverse DFT of complex data leaving the result in a. Complex number is stored as two double values in sequence: the real and imaginary part, i.e. the size of the input array must be greater or equal 2*n. The physical layout of the input data has to be as follows:
```
 a[offa+2*k] = Re[k], 
 a[offa+2*k+1] = Im[k], 0<=k<n
 
```
    Parameters:
    a - data to transform
    offa - index of the first element in array a
    scale - if true then scaling is performed
  - realForward
```
public void realForward(double[] a)
```
    Computes 1D forward DFT of real data leaving the result in a . The physical layout of the output data is as follows:
    if n is even then
```
 a[2*k] = Re[k], 0<=k<n/2
 a[2*k+1] = Im[k], 0<k<n/2
 a[1] = Re[n/2]
 
```
    if n is odd then
```
 a[2*k] = Re[k], 0<=k<(n+1)/2
 a[2*k+1] = Im[k], 0<k<(n-1)/2
 a[1] = Im[(n-1)/2]
 
```
    This method computes only half of the elements of the real transform. The other half satisfies the symmetry condition. If you want the full real forward transform, use realForwardFull. To get back the original data, use realInverse on the output of this method.
    Parameters:
    a - data to transform
  - realForward
```
public void realForward(double[] a,
               int offa)
```
    Computes 1D forward DFT of real data leaving the result in a . The physical layout of the output data is as follows:
    if n is even then
```
 a[offa+2*k] = Re[k], 0<=k<n/2
 a[offa+2*k+1] = Im[k], 0<k<n/2
 a[offa+1] = Re[n/2]
 
```
    if n is odd then
```
 a[offa+2*k] = Re[k], 0<=k<(n+1)/2
 a[offa+2*k+1] = Im[k], 0<k<(n-1)/2
 a[offa+1] = Im[(n-1)/2]
 
```
    This method computes only half of the elements of the real transform. The other half satisfies the symmetry condition. If you want the full real forward transform, use realForwardFull. To get back the original data, use realInverse on the output of this method.
    Parameters:
    a - data to transform
    offa - index of the first element in array a
  - realForwardFull
```
public void realForwardFull(double[] a)
```
    Computes 1D forward DFT of real data leaving the result in a . This method computes the full real forward transform, i.e. you will get the same result as from complexForward called with all imaginary parts equal 0. Because the result is stored in a, the size of the input array must greater or equal 2*n, with only the first n elements filled with real data. To get back the original data, use complexInverse on the output of this method.
    
    Parameters:
    a - data to transform
  - realForwardFull
```
public void realForwardFull(double[] a,
                   int offa)
```
    Computes 1D forward DFT of real data leaving the result in a . This method computes the full real forward transform, i.e. you will get the same result as from complexForward called with all imaginary part equal 0. Because the result is stored in a, the size of the input array must greater or equal 2*n, with only the first n elements filled with real data. To get back the original data, use complexInverse on the output of this method.
    
    Parameters:
    a - data to transform
    offa - index of the first element in array a
  - realInverse
```
public void realInverse(double[] a,
               boolean scale)
```
    Computes 1D inverse DFT of real data leaving the result in a . The physical layout of the input data has to be as follows:
    if n is even then
```
 a[2*k] = Re[k], 0<=k<n/2
 a[2*k+1] = Im[k], 0<k<n/2
 a[1] = Re[n/2]
 
```
    if n is odd then
```
 a[2*k] = Re[k], 0<=k<(n+1)/2
 a[2*k+1] = Im[k], 0<k<(n-1)/2
 a[1] = Im[(n-1)/2]
 
```
    This method computes only half of the elements of the real transform. The other half satisfies the symmetry condition. If you want the full real inverse transform, use realInverseFull.
    Parameters:
    a - data to transform
    scale - if true then scaling is performed
  - realInverse
```
public void realInverse(double[] a,
               int offa,
               boolean scale)
```
    Computes 1D inverse DFT of real data leaving the result in a . The physical layout of the input data has to be as follows:
    if n is even then
```
 a[offa+2*k] = Re[k], 0<=k<n/2
 a[offa+2*k+1] = Im[k], 0<k<n/2
 a[offa+1] = Re[n/2]
 
```
    if n is odd then
```
 a[offa+2*k] = Re[k], 0<=k<(n+1)/2
 a[offa+2*k+1] = Im[k], 0<k<(n-1)/2
 a[offa+1] = Im[(n-1)/2]
 
```
    This method computes only half of the elements of the real transform. The other half satisfies the symmetry condition. If you want the full real inverse transform, use realInverseFull.
    Parameters:
    a - data to transform
    offa - index of the first element in array a
    scale - if true then scaling is performed
  - realInverseFull
```
public void realInverseFull(double[] a,
                   boolean scale)
```
    Computes 1D inverse DFT of real data leaving the result in a . This method computes the full real inverse transform, i.e. you will get the same result as from complexInverse called with all imaginary part equal 0. Because the result is stored in a, the size of the input array must greater or equal 2*n, with only the first n elements filled with real data.
    
    Parameters:
    a - data to transform
    scale - if true then scaling is performed
  - realInverseFull
```
public void realInverseFull(double[] a,
                   int offa,
                   boolean scale)
```
    Computes 1D inverse DFT of real data leaving the result in a . This method computes the full real inverse transform, i.e. you will get the same result as from complexInverse called with all imaginary part equal 0. Because the result is stored in a, the size of the input array must greater or equal 2*n, with only the first n elements filled with real data.
    
    Parameters:
    a - data to transform
    offa - index of the first element in array a
    scale - if true then scaling is performed
  - realInverse2
```
protected void realInverse2(double[] a,
                int offa,
                boolean scale)
```

Class GeneralPurposeFFT_F64_1D

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

GeneralPurposeFFT_F64_1D

Method Detail

complexForward

complexForward

complexInverse

complexInverse

realForward

realForward

realForwardFull

realForwardFull

realInverse

realInverse

realInverseFull

realInverseFull

realInverse2