fft Class Reference

Fast fourier transform using the fftw library. More...

Public Types

enum  transformDirection { FORWARD_TRANSFORM = -1 , REVERSE_TRANSFORM = 1 }
 

Static Public Member Functions

static void fftRenumberRecurse (List< complex > &data, List< complex > &renumData, const UList< int > &nn, label nnprod, label ii, label l1, label l2)
 
static void fftRenumber (List< complex > &data, const UList< int > &nn)
 
static tmp< complexFieldrealTransform1D (const scalarField &field)
 Transform real-value data. More...
 
static tmp< complexFieldrealTransform1D (const tmp< scalarField > &field)
 Transform real-value data. More...
 
static void transform (complexField &field, const UList< int > &nn, transformDirection fftDirection)
 Transform complex-value data. More...
 
static tmp< complexFieldforwardTransform (const tmp< complexField > &field, const UList< int > &nn)
 
static tmp< complexFieldreverseTransform (const tmp< complexField > &field, const UList< int > &nn)
 
static tmp< complexVectorFieldforwardTransform (const tmp< complexVectorField > &field, const UList< int > &nn)
 
static tmp< complexVectorFieldreverseTransform (const tmp< complexVectorField > &field, const UList< int > &nn)
 

Detailed Description

Fast fourier transform using the fftw library.

The complex transform field is returned in the field supplied. The direction of transform is supplied as an argument (-1 = forward, 1 = reverse). The dimensionality and organisation of the array of values in space is supplied in the nn indexing array.

Note
The fftw library uses int only (no longs) for its dimensionality.
Source files

Definition at line 55 of file fft.H.

Member Enumeration Documentation

◆ transformDirection

Enumerator
FORWARD_TRANSFORM 

The sign -1 = FFTW_FORWARD.

REVERSE_TRANSFORM 

The sign +1 = FFTW_BACKWARD.

Definition at line 60 of file fft.H.

Member Function Documentation

◆ fftRenumberRecurse()

void fftRenumberRecurse ( List< complex > &  data,
List< complex > &  renumData,
const UList< int > &  nn,
label  nnprod,
label  ii,
label  l1,
label  l2 
)
static

Definition at line 34 of file fft.C.

References fft::fftRenumberRecurse(), Foam::Im(), Foam::Re(), and UList< T >::size().

Referenced by fft::fftRenumberRecurse().

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◆ fftRenumber()

void fftRenumber ( List< complex > &  data,
const UList< int > &  nn 
)
static

fftRenumber: fold the n-d data array to get the fft components in the right places.

Definition at line 94 of file fft.C.

References forAll.

◆ realTransform1D() [1/2]

Foam::tmp< Foam::complexField > realTransform1D ( const scalarField field)
static

Transform real-value data.

  • uses the fftw real to half-complex method

result size is field.size()/2 + 1

Definition at line 120 of file fft.C.

References UList< T >::data(), field(), n, and Time::New().

Referenced by noiseModel::Pf(), and noiseFFT::Pf().

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◆ realTransform1D() [2/2]

Foam::tmp< Foam::complexField > realTransform1D ( const tmp< scalarField > &  field)
static

Transform real-value data.

  • uses the fftw real to half-complex method

result size is field.size()/2 + 1

Definition at line 167 of file fft.C.

References tmp< T >::clear().

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◆ transform()

void transform ( complexField field,
const UList< int > &  nn,
transformDirection  fftDirection 
)
static

Transform complex-value data.

Definition at line 178 of file fft.C.

References UList< T >::begin(), field(), forAll, N(), and UList< T >::size().

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◆ forwardTransform() [1/2]

Foam::tmp< Foam::complexField > forwardTransform ( const tmp< complexField > &  field,
const UList< int > &  nn 
)
static

Definition at line 242 of file fft.C.

References tmp< T >::clear(), Time::New(), and Foam::transform().

Referenced by energySpectrum::calcAndWriteSpectrum(), and Foam::calcEk().

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◆ reverseTransform() [1/2]

Foam::tmp< Foam::complexField > reverseTransform ( const tmp< complexField > &  field,
const UList< int > &  nn 
)
static

Definition at line 258 of file fft.C.

References tmp< T >::clear(), Time::New(), and Foam::transform().

Referenced by turbGen::U().

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◆ forwardTransform() [2/2]

Foam::tmp< Foam::complexVectorField > forwardTransform ( const tmp< complexVectorField > &  field,
const UList< int > &  nn 
)
static

Definition at line 274 of file fft.C.

References tmp< T >::clear(), Foam::component(), pTraits< bool >::nComponents, and Time::New().

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◆ reverseTransform() [2/2]

Foam::tmp< Foam::complexVectorField > reverseTransform ( const tmp< complexVectorField > &  field,
const UList< int > &  nn 
)
static

Definition at line 297 of file fft.C.

References tmp< T >::clear(), Foam::component(), pTraits< bool >::nComponents, and Time::New().

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The documentation for this class was generated from the following files: