One of the interface classes to the FFTW package, can be used directly or via the TVirtualFFT class.

Only the basic interface of FFTW is implemented.

Computes transforms called r2r in FFTW manual:

transforms of real input and output in "halfcomplex" format i.e. real and imaginary parts for a transform of size n stored as (r0, r1, r2, ..., rn/2, i(n+1)/2-1, ..., i2, i1)
discrete Hartley transform
sine and cosine transforms (DCT-I,II,III,IV and DST-I,II,III,IV) For the detailed information on the computed transforms please refer to the FFTW manual, chapter "What FFTW really computes".

How to use it:

Create an instance of TFFTReal - this will allocate input and output arrays (unless an in-place transform is specified)
Run the Init() function with the desired flags and settings (see function comments for possible kind parameters)
Set the data (via SetPoints()or SetPoint() functions)
Run the Transform() function
Get the output (via GetPoints() or GetPoint() functions)
Repeat steps 3)-5) as needed

For a transform of the same size, but of different kind (or with different flags), rerun the Init() function and continue with steps 3)-5)

NOTE:

running Init() function will overwrite the input array! Don't set any data before running the Init() function!
FFTW computes unnormalized transform, so doing a transform followed by its inverse will lead to the original array scaled BY:
- transform size (N) for R2HC, HC2R, DHT transforms
- 2*(N-1) for DCT-I (REDFT00)
- 2*(N+1) for DST-I (RODFT00)
- 2*N for the remaining transforms

Transform inverses:

R2HC<-->HC2R
DHT<-->DHT
DCT-I<-->DCT-I
DCT-II<-->DCT-III
DCT-IV<-->DCT-IV
DST-I<-->DST-I
DST-II<-->DST-III
DST-IV<-->DST-IV

Definition at line 20 of file TFFTReal.h.

Public Member Functions
	TFFTReal ()
	default

	TFFTReal (Int_t n, Bool_t inPlace=kFALSE)
	For 1d transforms n here is the physical size of the transform (see FFTW manual for more details)

	TFFTReal (Int_t ndim, Int_t *n, Bool_t inPlace=kFALSE)
	For multidimensional transforms 1st parameter is the # of dimensions, 2nd is the sizes (physical) of the transform in each dimension.

virtual	~TFFTReal ()
	clean-up

virtual Int_t *	GetN () const

virtual Int_t	GetNdim () const

virtual void	GetPointComplex (const Int_t *ipoint, Double_t &re, Double_t &im, Bool_t fromInput=kFALSE) const
	Only for input of HC2R and output of R2HC and for 1d.

virtual void	GetPointComplex (Int_t ipoint, Double_t &re, Double_t &im, Bool_t fromInput=kFALSE) const
	Only for input of HC2R and output of R2HC.

virtual Double_t	GetPointReal (const Int_t *ipoint, Bool_t fromInput=kFALSE) const
	For multidim.transforms. Returns point #ipoint.

virtual Double_t	GetPointReal (Int_t ipoint, Bool_t fromInput=kFALSE) const
	For 1d tranforms. Returns point #ipoint.

virtual void	GetPoints (Double_t *data, Bool_t fromInput=kFALSE) const
	Copies the output (or input) points into the provided array, that should be big enough.

virtual void	GetPointsComplex (Double_t *, Bool_t) const

virtual void	GetPointsComplex (Double_t , Double_t , Bool_t) const

virtual Double_t *	GetPointsReal (Bool_t fromInput=kFALSE) const
	Returns the output (or input) array we have 4 different cases:

virtual Int_t	GetSign () const

virtual Int_t	GetSize () const

virtual Option_t *	GetTransformFlag () const

virtual Option_t *	GetType () const
	Returns the type of the transform.

virtual void	Init (Option_t flags, Int_t sign, const Int_t kind)
	Creates the fftw-plan.

virtual Bool_t	IsInplace () const

virtual void	SetPoint (const Int_t *ipoint, Double_t re, Double_t)
	Since multidimensional R2HC and HC2R transforms are not supported, third parameter is dummy.

virtual void	SetPoint (Int_t ipoint, Double_t re, Double_t im=0)

virtual void	SetPointComplex (Int_t, TComplex &)

virtual void	SetPoints (const Double_t *data)
	Sets all points.

virtual void	SetPointsComplex (const Double_t , const Double_t )

virtual void	Transform ()
	Computes the transform, specified in Init() function.

Public Member Functions inherited from TVirtualFFT
	TVirtualFFT ()

virtual	~TVirtualFFT ()
	destructor

Public Member Functions inherited from TObject
	TObject ()
	TObject constructor.

	TObject (const TObject &object)
	TObject copy ctor.

virtual	~TObject ()
	TObject destructor.

void	AbstractMethod (const char *method) const
	Use this method to implement an "abstract" method that you don't want to leave purely abstract.

virtual void	AppendPad (Option_t *option="")
	Append graphics object to current pad.

virtual void	Browse (TBrowser *b)
	Browse object. May be overridden for another default action.

ULong_t	CheckedHash ()
	Check and record whether this class has a consistent Hash/RecursiveRemove setup (*) and then return the regular Hash value for this object.

virtual const char *	ClassName () const
	Returns name of class to which the object belongs.

virtual void	Clear (Option_t *="")

virtual TObject *	Clone (const char *newname="") const
	Make a clone of an object using the Streamer facility.

virtual Int_t	Compare (const TObject *obj) const
	Compare abstract method.

virtual void	Copy (TObject &object) const
	Copy this to obj.

virtual void	Delete (Option_t *option="")
	Delete this object.

virtual Int_t	DistancetoPrimitive (Int_t px, Int_t py)
	Computes distance from point (px,py) to the object.

virtual void	Draw (Option_t *option="")
	Default Draw method for all objects.

virtual void	DrawClass () const
	Draw class inheritance tree of the class to which this object belongs.

virtual TObject *	DrawClone (Option_t *option="") const
	Draw a clone of this object in the current selected pad for instance with: `gROOT->SetSelectedPad(gPad)`.

virtual void	Dump () const
	Dump contents of object on stdout.

virtual void	Error (const char method, const char msgfmt,...) const
	Issue error message.

virtual void	Execute (const char method, const char params, Int_t *error=0)
	Execute method on this object with the given parameter string, e.g.

virtual void	Execute (TMethod method, TObjArray params, Int_t *error=0)
	Execute method on this object with parameters stored in the TObjArray.

virtual void	ExecuteEvent (Int_t event, Int_t px, Int_t py)
	Execute action corresponding to an event at (px,py).

virtual void	Fatal (const char method, const char msgfmt,...) const
	Issue fatal error message.

virtual TObject *	FindObject (const char *name) const
	Must be redefined in derived classes.

virtual TObject *	FindObject (const TObject *obj) const
	Must be redefined in derived classes.

virtual Option_t *	GetDrawOption () const
	Get option used by the graphics system to draw this object.

virtual const char *	GetIconName () const
	Returns mime type name of object.

virtual const char *	GetName () const
	Returns name of object.

virtual char *	GetObjectInfo (Int_t px, Int_t py) const
	Returns string containing info about the object at position (px,py).

virtual Option_t *	GetOption () const

virtual const char *	GetTitle () const
	Returns title of object.

virtual UInt_t	GetUniqueID () const
	Return the unique object id.

virtual Bool_t	HandleTimer (TTimer *timer)
	Execute action in response of a timer timing out.

virtual ULong_t	Hash () const
	Return hash value for this object.

Bool_t	HasInconsistentHash () const
	Return true is the type of this object is known to have an inconsistent setup for Hash and RecursiveRemove (i.e.

virtual void	Info (const char method, const char msgfmt,...) const
	Issue info message.

virtual Bool_t	InheritsFrom (const char *classname) const
	Returns kTRUE if object inherits from class "classname".

virtual Bool_t	InheritsFrom (const TClass *cl) const
	Returns kTRUE if object inherits from TClass cl.

virtual void	Inspect () const
	Dump contents of this object in a graphics canvas.

void	InvertBit (UInt_t f)

virtual Bool_t	IsEqual (const TObject *obj) const
	Default equal comparison (objects are equal if they have the same address in memory).

virtual Bool_t	IsFolder () const
	Returns kTRUE in case object contains browsable objects (like containers or lists of other objects).

R__ALWAYS_INLINE Bool_t	IsOnHeap () const

virtual Bool_t	IsSortable () const

R__ALWAYS_INLINE Bool_t	IsZombie () const

virtual void	ls (Option_t *option="") const
	The ls function lists the contents of a class on stdout.

void	MayNotUse (const char *method) const
	Use this method to signal that a method (defined in a base class) may not be called in a derived class (in principle against good design since a child class should not provide less functionality than its parent, however, sometimes it is necessary).

virtual Bool_t	Notify ()
	This method must be overridden to handle object notification.

void	Obsolete (const char method, const char asOfVers, const char *removedFromVers) const
	Use this method to declare a method obsolete.

void	operator delete (void *ptr)
	Operator delete.

void	operator delete[] (void *ptr)
	Operator delete [].

void *	operator new (size_t sz)

void *	operator new (size_t sz, void *vp)

void *	operator new[] (size_t sz)

void *	operator new[] (size_t sz, void *vp)

TObject &	operator= (const TObject &rhs)
	TObject assignment operator.

virtual void	Paint (Option_t *option="")
	This method must be overridden if a class wants to paint itself.

virtual void	Pop ()
	Pop on object drawn in a pad to the top of the display list.

virtual void	Print (Option_t *option="") const
	This method must be overridden when a class wants to print itself.

virtual Int_t	Read (const char *name)
	Read contents of object with specified name from the current directory.

virtual void	RecursiveRemove (TObject *obj)
	Recursively remove this object from a list.

void	ResetBit (UInt_t f)

virtual void	SaveAs (const char filename="", Option_t option="") const
	Save this object in the file specified by filename.

virtual void	SavePrimitive (std::ostream &out, Option_t *option="")
	Save a primitive as a C++ statement(s) on output stream "out".

void	SetBit (UInt_t f)

void	SetBit (UInt_t f, Bool_t set)
	Set or unset the user status bits as specified in f.

virtual void	SetDrawOption (Option_t *option="")
	Set drawing option for object.

virtual void	SetUniqueID (UInt_t uid)
	Set the unique object id.

virtual void	SysError (const char method, const char msgfmt,...) const
	Issue system error message.

R__ALWAYS_INLINE Bool_t	TestBit (UInt_t f) const

Int_t	TestBits (UInt_t f) const

virtual void	UseCurrentStyle ()
	Set current style settings in this object This function is called when either TCanvas::UseCurrentStyle or TROOT::ForceStyle have been invoked.

virtual void	Warning (const char method, const char msgfmt,...) const
	Issue warning message.

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0)
	Write this object to the current directory.

virtual Int_t	Write (const char *name=0, Int_t option=0, Int_t bufsize=0) const
	Write this object to the current directory.

Protected Member Functions
UInt_t	MapFlag (Option_t *flag)
	allowed options:

Int_t	MapOptions (const Int_t *kind)
	transfers the r2r_kind parameters to fftw type

Protected Member Functions inherited from TObject
virtual void	DoError (int level, const char location, const char fmt, va_list va) const
	Interface to ErrorHandler (protected).

void	MakeZombie ()

Protected Attributes
TString	fFlags

void *	fIn

void *	fKind

Int_t *	fN

Int_t	fNdim

void *	fOut

void *	fPlan

Int_t	fTotalSize

Additional Inherited Members
Public Types inherited from TObject
enum	{ kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 , kBitMask = 0x00ffffff }

enum	{ kSingleKey = BIT(0) , kOverwrite = BIT(1) , kWriteDelete = BIT(2) }

enum	EDeprecatedStatusBits { kObjInCanvas = BIT(3) }

enum	EStatusBits { kCanDelete = BIT(0) , kMustCleanup = BIT(3) , kIsReferenced = BIT(4) , kHasUUID = BIT(5) , kCannotPick = BIT(6) , kNoContextMenu = BIT(8) , kInvalidObject = BIT(13) }

Static Public Member Functions inherited from TVirtualFFT
static TVirtualFFT *	FFT (Int_t ndim, Int_t n, Option_t option)
	Returns a pointer to the FFT of requested size and type.

static TVirtualFFT *	GetCurrentTransform ()
	static: return current fgFFT

static const char *	GetDefaultFFT ()
	static: return the name of the default fft

static void	SetDefaultFFT (const char *name="")
	static: set name of default fft

static void	SetTransform (TVirtualFFT *fft)
	static: set the current transfrom to parameter

static TVirtualFFT *	SineCosine (Int_t ndim, Int_t n, Int_t r2rkind, Option_t *option)
	Returns a pointer to a sine or cosine transform of requested size and kind.

Static Public Member Functions inherited from TObject
static Long_t	GetDtorOnly ()
	Return destructor only flag.

static Bool_t	GetObjectStat ()
	Get status of object stat flag.

static void	SetDtorOnly (void *obj)
	Set destructor only flag.

static void	SetObjectStat (Bool_t stat)
	Turn on/off tracking of objects in the TObjectTable.

Protected Types inherited from TObject
enum	{ kOnlyPrepStep = BIT(3) }

Static Protected Attributes inherited from TVirtualFFT
static TString	fgDefault = ""

static TVirtualFFT *	fgFFT = 0

#include <TFFTReal.h>

Inheritance diagram for TFFTReal:

[legend]

Constructor & Destructor Documentation

◆ TFFTReal() [1/3]

TFFTReal::TFFTReal ( )

default

Definition at line 69 of file TFFTReal.cxx.

◆ TFFTReal() [2/3]

TFFTReal::TFFTReal	(	Int_t	n,
		Bool_t	inPlace = `kFALSE`
	)

For 1d transforms n here is the physical size of the transform (see FFTW manual for more details)

Definition at line 84 of file TFFTReal.cxx.

◆ TFFTReal() [3/3]

TFFTReal::TFFTReal	(	Int_t	ndim,
		Int_t *	n,
		Bool_t	inPlace = `kFALSE`
	)

For multidimensional transforms 1st parameter is the # of dimensions, 2nd is the sizes (physical) of the transform in each dimension.

Definition at line 103 of file TFFTReal.cxx.

◆ ~TFFTReal()

TFFTReal::~TFFTReal ( )

virtual

clean-up

Definition at line 124 of file TFFTReal.cxx.

Member Function Documentation

◆ GetN()

virtual Int_t * TFFTReal::GetN ( ) const

inlinevirtual

Implements TVirtualFFT.

Definition at line 43 of file TFFTReal.h.

◆ GetNdim()

virtual Int_t TFFTReal::GetNdim ( ) const

inlinevirtual

Implements TVirtualFFT.

Definition at line 44 of file TFFTReal.h.

◆ GetPointComplex() [1/2]

void TFFTReal::GetPointComplex	(	const Int_t *	ipoint,
		Double_t &	re,
		Double_t &	im,
		Bool_t	fromInput = `kFALSE`
	)		const

virtual

Only for input of HC2R and output of R2HC and for 1d.

Implements TVirtualFFT.

Definition at line 282 of file TFFTReal.cxx.

◆ GetPointComplex() [2/2]

void TFFTReal::GetPointComplex	(	Int_t	ipoint,
		Double_t &	re,
		Double_t &	im,
		Bool_t	fromInput = `kFALSE`
	)		const

virtual

Only for input of HC2R and output of R2HC.

Implements TVirtualFFT.

Definition at line 262 of file TFFTReal.cxx.

◆ GetPointReal() [1/2]

Double_t TFFTReal::GetPointReal	(	const Int_t *	ipoint,
		Bool_t	fromInput = `kFALSE`
	)		const

virtual

For multidim.transforms. Returns point #ipoint.

Implements TVirtualFFT.

Definition at line 249 of file TFFTReal.cxx.

◆ GetPointReal() [2/2]

Double_t TFFTReal::GetPointReal	(	Int_t	ipoint,
		Bool_t	fromInput = `kFALSE`
	)		const

virtual

For 1d tranforms. Returns point #ipoint.

Implements TVirtualFFT.

Definition at line 236 of file TFFTReal.cxx.

◆ GetPoints()

void TFFTReal::GetPoints	(	Double_t *	data,
		Bool_t	fromInput = `kFALSE`
	)		const

virtual

Copies the output (or input) points into the provided array, that should be big enough.

Implements TVirtualFFT.

Definition at line 226 of file TFFTReal.cxx.

◆ GetPointsComplex() [1/2]

virtual void TFFTReal::GetPointsComplex	(	Double_t *	,
		Bool_t
	)		const

inlinevirtual

Implements TVirtualFFT.

Definition at line 59 of file TFFTReal.h.

◆ GetPointsComplex() [2/2]

virtual void TFFTReal::GetPointsComplex	(	Double_t *	,
		Double_t *	,
		Bool_t
	)		const

inlinevirtual

Implements TVirtualFFT.

Definition at line 58 of file TFFTReal.h.

◆ GetPointsReal()

Double_t * TFFTReal::GetPointsReal ( Bool_t fromInput = kFALSE ) const

virtual

Returns the output (or input) array we have 4 different cases:

fromInput = false; fOut = !NULL (transformed is not in place) : return fOut
- fromInput = false; fOut = NULL (transformed is in place) : return fIn
fromInput = true; fOut = !NULL : return fIn
fromInput = true; fOut = NULL return an error since input array is overwritten

Implements TVirtualFFT.

Definition at line 296 of file TFFTReal.cxx.

◆ GetSign()

virtual Int_t TFFTReal::GetSign ( ) const

inlinevirtual

Implements TVirtualFFT.

Definition at line 46 of file TFFTReal.h.

◆ GetSize()

virtual Int_t TFFTReal::GetSize ( ) const

inlinevirtual

Definition at line 42 of file TFFTReal.h.

◆ GetTransformFlag()

virtual Option_t * TFFTReal::GetTransformFlag ( ) const

inlinevirtual

Implements TVirtualFFT.

Definition at line 47 of file TFFTReal.h.

◆ GetType()

Option_t * TFFTReal::GetType ( ) const

virtual

Returns the type of the transform.

Implements TVirtualFFT.

Definition at line 210 of file TFFTReal.cxx.

◆ Init()

void TFFTReal::Init	(	Option_t *	flags,
		Int_t	sign,
		const Int_t *	kind
	)

virtual

Creates the fftw-plan.

NOTE: input and output arrays are overwritten during initialisation, so don't set any points, before running this function!!!!!

1st parameter:

Possible flag_options:

"ES" (from "estimate") - no time in preparing the transform, but probably sub-optimal performance
"M" (from "measure") - some time spend in finding the optimal way to do the transform
"P" (from "patient") - more time spend in finding the optimal way to do the transform
"EX" (from "exhaustive") - the most optimal way is found

This option should be chosen depending on how many transforms of the same size and type are going to be done. Planning is only done once, for the first transform of this size and type.

2nd parameter:

is dummy and doesn't need to be specified

3rd parameter:

transform kind for each dimension 4 different kinds of sine and cosine transforms are available

DCT-I - kind=0
DCT-II - kind=1
DCT-III - kind=2
DCT-IV - kind=3
DST-I - kind=4
DST-II - kind=5
DSTIII - kind=6
DSTIV - kind=7

Implements TVirtualFFT.

Definition at line 176 of file TFFTReal.cxx.

◆ IsInplace()

virtual Bool_t TFFTReal::IsInplace ( ) const

inlinevirtual

Implements TVirtualFFT.

Definition at line 48 of file TFFTReal.h.

◆ MapFlag()

UInt_t TFFTReal::MapFlag ( Option_t * flag )

protected

allowed options:

"ES" - FFTW_ESTIMATE
"M" - FFTW_MEASURE
"P" - FFTW_PATIENT
"EX" - FFTW_EXHAUSTIVE

Definition at line 403 of file TFFTReal.cxx.

◆ MapOptions()

Int_t TFFTReal::MapOptions ( const Int_t * kind )

protected

transfers the r2r_kind parameters to fftw type

Definition at line 357 of file TFFTReal.cxx.

◆ SetPoint() [1/2]

void TFFTReal::SetPoint	(	const Int_t *	ipoint,
		Double_t	re,
		Double_t
	)

virtual

Since multidimensional R2HC and HC2R transforms are not supported, third parameter is dummy.

Implements TVirtualFFT.

Definition at line 333 of file TFFTReal.cxx.

◆ SetPoint() [2/2]

void TFFTReal::SetPoint	(	Int_t	ipoint,
		Double_t	re,
		Double_t	im = `0`
	)

virtual

Implements TVirtualFFT.

Definition at line 311 of file TFFTReal.cxx.

◆ SetPointComplex()

virtual void TFFTReal::SetPointComplex	(	Int_t	,
		TComplex &
	)

inlinevirtual

Implements TVirtualFFT.

Definition at line 64 of file TFFTReal.h.

◆ SetPoints()

void TFFTReal::SetPoints ( const Double_t * data )

virtual

Sets all points.

Implements TVirtualFFT.

Definition at line 348 of file TFFTReal.cxx.

◆ SetPointsComplex()

virtual void TFFTReal::SetPointsComplex	(	const Double_t *	,
		const Double_t *
	)

inlinevirtual

Implements TVirtualFFT.

Definition at line 65 of file TFFTReal.h.

◆ Transform()

void TFFTReal::Transform ( )

virtual

Computes the transform, specified in Init() function.

Implements TVirtualFFT.

Definition at line 197 of file TFFTReal.cxx.

Member Data Documentation

◆ fFlags

TString TFFTReal::fFlags

protected

Definition at line 29 of file TFFTReal.h.

◆ fIn

void* TFFTReal::fIn

protected

Definition at line 22 of file TFFTReal.h.

◆ fKind

void* TFFTReal::fKind

protected

Definition at line 28 of file TFFTReal.h.

◆ fN

Int_t* TFFTReal::fN

protected

Definition at line 27 of file TFFTReal.h.

◆ fNdim

Int_t TFFTReal::fNdim

protected

Definition at line 25 of file TFFTReal.h.

◆ fOut

void* TFFTReal::fOut

protected

Definition at line 23 of file TFFTReal.h.

◆ fPlan

void* TFFTReal::fPlan

protected

Definition at line 24 of file TFFTReal.h.

◆ fTotalSize

Int_t TFFTReal::fTotalSize

protected

Definition at line 26 of file TFFTReal.h.

Libraries for TFFTReal:

[legend]

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

math/fftw/inc/TFFTReal.h
math/fftw/src/TFFTReal.cxx

Public Member Functions

Protected Member Functions

Protected Attributes

Additional Inherited Members

Constructor & Destructor Documentation

◆ TFFTReal() [1/3]

◆ TFFTReal() [2/3]

◆ TFFTReal() [3/3]

◆ ~TFFTReal()

Member Function Documentation

◆ GetN()

◆ GetNdim()

◆ GetPointComplex() [1/2]

◆ GetPointComplex() [2/2]

◆ GetPointReal() [1/2]

◆ GetPointReal() [2/2]

◆ GetPoints()

◆ GetPointsComplex() [1/2]

◆ GetPointsComplex() [2/2]

◆ GetPointsReal()

◆ GetSign()

◆ GetSize()

◆ GetTransformFlag()

◆ GetType()

◆ Init()

1st parameter:

2nd parameter:

3rd parameter:

◆ IsInplace()

◆ MapFlag()

◆ MapOptions()

◆ SetPoint() [1/2]

◆ SetPoint() [2/2]

◆ SetPointComplex()

◆ SetPoints()

◆ SetPointsComplex()

◆ Transform()

Member Data Documentation

◆ fFlags

◆ fIn

◆ fKind

◆ fN

◆ fNdim

◆ fOut

◆ fPlan

◆ fTotalSize