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TFFTReal Class Reference

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:

1. Create an instance of TFFTReal - this will allocate input and output arrays (unless an in-place transform is specified)
2. Run the Init() function with the desired flags and settings (see function comments for possible kind parameters)
3. Set the data (via SetPoints()or SetPoint() functions)
4. Run the Transform() function
5. Get the output (via GetPoints() or GetPoint() functions)
6. 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:

1. running Init() function will overwrite the input array! Don't set any data before running the Init() function!
2. 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.

~TFFTReal () override
clean-up

Int_tGetN () const override

Int_t GetNdim () const override

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

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

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

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

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

void GetPointsComplex (Double_t *, Bool_t) const override

void GetPointsComplex (Double_t *, Double_t *, Bool_t) const override

Double_tGetPointsReal (Bool_t fromInput=kFALSE) const override
Returns the output (or input) array we have 4 different cases:

Int_t GetSign () const override

virtual Int_t GetSize () const

Option_tGetTransformFlag () const override

Option_tGetType () const override
Returns the type of the transform.

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

TClassIsA () const override

Bool_t IsInplace () const override

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

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

void SetPointComplex (Int_t, TComplex &) override

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

void SetPointsComplex (const Double_t *, const Double_t *) override

void Streamer (TBuffer &) override
Stream an object of class TObject.

void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

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

Public Member Functions inherited from TVirtualFFT
TVirtualFFT ()

virtual ~TVirtualFFT ()
destructor

TClassIsA () const override

void Streamer (TBuffer &) override
Stream an object of class TObject.

void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

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.

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 TObjectClone (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 TObjectDrawClone (Option_t *option="") const
Draw a clone of this object in the current selected pad with: gROOT->SetSelectedPad(c1).

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=nullptr)
Execute method on this object with the given parameter string, e.g.

virtual void Execute (TMethod *method, TObjArray *params, Int_t *error=nullptr)
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 TObjectFindObject (const char *name) const
Must be redefined in derived classes.

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

virtual Option_tGetDrawOption () 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_tGetOption () 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)

Bool_t IsDestructed () const
IsDestructed.

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 (the base implementation is no-op).

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, void *vp)
Only called by placement new when throwing an exception.

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

void operator delete[] (void *ptr, void *vp)
Only called by placement new[] when throwing an exception.

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)

TObjectoperator= (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.

void StreamerNVirtual (TBuffer &ClassDef_StreamerNVirtual_b)

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=nullptr, Int_t option=0, Int_t bufsize=0)
Write this object to the current directory.

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

## Static Public Member Functions

static TClassClass ()

static const char * Class_Name ()

static constexpr Version_t Class_Version ()

static const char * DeclFileName ()

Static Public Member Functions inherited from TVirtualFFT
static TClassClass ()

static const char * Class_Name ()

static constexpr Version_t Class_Version ()

static const char * DeclFileName ()

static TVirtualFFTFFT (Int_t ndim, Int_t *n, Option_t *option)
Returns a pointer to the FFT of requested size and type.

static TVirtualFFTGetCurrentTransform ()
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 TVirtualFFTSineCosine (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 TClassClass ()

static const char * Class_Name ()

static constexpr Version_t Class_Version ()

static const char * DeclFileName ()

static Longptr_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 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_tfN

Int_t fNdim

void * fOut

void * fPlan

Int_t fTotalSize

Public Types inherited from TObject
enum  {
kIsOnHeap = 0x01000000 , kNotDeleted = 0x02000000 , kZombie = 0x04000000 , kInconsistent = 0x08000000 ,
}

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

enum  EDeprecatedStatusBits { kObjInCanvas = (1ULL << ( 3 )) }

enum  EStatusBits {
kCanDelete = (1ULL << ( 0 )) , kMustCleanup = (1ULL << ( 3 )) , kIsReferenced = (1ULL << ( 4 )) , kHasUUID = (1ULL << ( 5 )) ,
kCannotPick = (1ULL << ( 6 )) , kNoContextMenu = (1ULL << ( 8 )) , kInvalidObject = (1ULL << ( 13 ))
}

Protected Types inherited from TObject
enum  { kOnlyPrepStep = (1ULL << ( 3 )) }

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

static TVirtualFFTfgFFT = nullptr

#include <TFFTReal.h>

Inheritance diagram for TFFTReal:
[legend]

## ◆ 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 ( )
override

clean-up

Definition at line 124 of file TFFTReal.cxx.

## ◆ Class()

 static TClass * TFFTReal::Class ( )
static
Returns
TClass describing this class

## ◆ Class_Name()

 static const char * TFFTReal::Class_Name ( )
static
Returns
Name of this class

## ◆ Class_Version()

 static constexpr Version_t TFFTReal::Class_Version ( )
inlinestaticconstexpr
Returns
Version of this class

Definition at line 69 of file TFFTReal.h.

## ◆ DeclFileName()

 static const char * TFFTReal::DeclFileName ( )
inlinestatic
Returns
Name of the file containing the class declaration

Definition at line 69 of file TFFTReal.h.

## ◆ GetN()

 Int_t * TFFTReal::GetN ( ) const
inlineoverridevirtual

Implements TVirtualFFT.

Definition at line 43 of file TFFTReal.h.

## ◆ GetNdim()

 Int_t TFFTReal::GetNdim ( ) const
inlineoverridevirtual

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
overridevirtual

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
overridevirtual

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
overridevirtual

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
overridevirtual

For 1d transformations. 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
overridevirtual

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]

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

Implements TVirtualFFT.

Definition at line 59 of file TFFTReal.h.

## ◆ GetPointsComplex() [2/2]

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

Implements TVirtualFFT.

Definition at line 58 of file TFFTReal.h.

## ◆ GetPointsReal()

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

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()

 Int_t TFFTReal::GetSign ( ) const
inlineoverridevirtual

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()

 Option_t * TFFTReal::GetTransformFlag ( ) const
inlineoverridevirtual

Implements TVirtualFFT.

Definition at line 47 of file TFFTReal.h.

## ◆ GetType()

 Option_t * TFFTReal::GetType ( ) const
overridevirtual

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 )
overridevirtual

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.

## ◆ IsA()

 TClass * TFFTReal::IsA ( ) const
inlineoverridevirtual
Returns
TClass describing current object

Reimplemented from TObject.

Definition at line 69 of file TFFTReal.h.

## ◆ IsInplace()

 Bool_t TFFTReal::IsInplace ( ) const
inlineoverridevirtual

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 )
overridevirtual

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 )
overridevirtual

Implements TVirtualFFT.

Definition at line 311 of file TFFTReal.cxx.

## ◆ SetPointComplex()

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

Implements TVirtualFFT.

Definition at line 64 of file TFFTReal.h.

## ◆ SetPoints()

 void TFFTReal::SetPoints ( const Double_t * data )
overridevirtual

Sets all points.

Implements TVirtualFFT.

Definition at line 348 of file TFFTReal.cxx.

## ◆ SetPointsComplex()

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

Implements TVirtualFFT.

Definition at line 65 of file TFFTReal.h.

## ◆ Streamer()

 void TFFTReal::Streamer ( TBuffer & R__b )
overridevirtual

Stream an object of class TObject.

Reimplemented from TObject.

## ◆ StreamerNVirtual()

 void TFFTReal::StreamerNVirtual ( TBuffer & ClassDef_StreamerNVirtual_b )
inline

Definition at line 69 of file TFFTReal.h.

## ◆ Transform()

 void TFFTReal::Transform ( )
overridevirtual

Computes the transform, specified in Init() function.

Implements TVirtualFFT.

Definition at line 197 of file TFFTReal.cxx.

## ◆ 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:

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