// @(#)root/base:$Name: $:$Id: TVirtualFFT.h,v 1.3 2006/10/27 16:21:11 brun Exp $ // Author: Anna Kreshuk 10/04/2006 #ifndef ROOT_TVirtualFFT #define ROOT_TVirtualFFT ////////////////////////////////////////////////////////////////////////// // // TVirtualFFT // // TVirtualFFT is an interface class for Fast Fourier Transforms. // // // // The default FFT library is FFTW. To use it, FFTW3 library should already // be installed, and ROOT should be have fftw3 module enabled, with the directories // of fftw3 include file and library specified (see installation instructions). // Function SetDefaultFFT() allows to change the default library. // // Available transform types: // FFT: // - "C2CFORWARD" - a complex input/output discrete Fourier transform (DFT) // in one or more dimensions, -1 in the exponent // - "C2CBACKWARD"- a complex input/output discrete Fourier transform (DFT) // in one or more dimensions, +1 in the exponent // - "R2C" - a real-input/complex-output discrete Fourier transform (DFT) // in one or more dimensions, // - "C2R" - inverse transforms to "R2C", taking complex input // (storing the non-redundant half of a logically Hermitian array) // to real output // - "R2HC" - a real-input DFT with output in ¡Èhalfcomplex¡É 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 // - "HC2R" - computes the reverse of FFTW_R2HC, above // - "DHT" - computes a discrete Hartley transform // // Sine/cosine transforms: // Different types of transforms are specified by parameter kind of the SineCosine() static // function. 4 different kinds of sine and cosine transforms are available // DCT-I (REDFT00 in FFTW3 notation)- kind=0 // DCT-II (REDFT10 in FFTW3 notation)- kind=1 // DCT-III(REDFT01 in FFTW3 notation)- kind=2 // DCT-IV (REDFT11 in FFTW3 notation)- kind=3 // DST-I (RODFT00 in FFTW3 notation)- kind=4 // DST-II (RODFT10 in FFTW3 notation)- kind=5 // DST-III(RODFT01 in FFTW3 notation)- kind=6 // DST-IV (RODFT11 in FFTW3 notation)- kind=7 // Formulas and detailed descriptions can be found in the chapter // "What FFTW really computes" of the FFTW manual // // NOTE: FFTW computes unnormalized transforms, so doing a transform, followed by its // inverse will give the original array, multiplied by normalization constant // (transform size(N) for FFT, 2*(N-1) for DCT-I, 2*(N+1) for DST-I, 2*N for // other sine/cosine transforms) // // How to use it: // Call to the static function FFT returns a pointer to a fast fourier transform // with requested parameters. Call to the static function SineCosine returns a // pointer to a sine or cosine transform with requested parameters. Example: // { // Int_t N = 10; Double_t *in = new Double_t[N]; // TVirtualFFT *fftr2c = TVirtualFFT::FFT(1, &N, "R2C"); // fftr2c->SetPoints(in); // fftr2c->Transform(); // Double_t re, im; // for (Int_t i=0; i<N; i++) // fftr2c->GetPointComplex(i, re, im); // ... // fftr2c->SetPoints(in2); // ... // fftr2c->SetPoints(in3); // ... // } // Different options are explained in the function comments // // // // // ////////////////////////////////////////////////////////////////////////// #ifndef ROOT_TObject #include "TObject.h" #endif #ifndef ROOT_TString #include "TString.h" #endif class TComplex; class TVirtualFFT: public TObject { protected: static TVirtualFFT *fgFFT; //current transformer static TString fgDefault; //default transformer public: TVirtualFFT(){}; virtual ~TVirtualFFT(); virtual Int_t *GetN() const = 0; virtual Int_t GetNdim() const = 0; virtual Option_t *GetType() const = 0; virtual Int_t GetSign() const = 0; virtual Option_t *GetTransformFlag() const = 0; virtual void Init(Option_t *flag,Int_t sign, const Int_t *kind) = 0; virtual Bool_t IsInplace() const = 0; virtual void GetPoints(Double_t *data, Bool_t fromInput = kFALSE) const = 0; virtual Double_t GetPointReal(Int_t ipoint, Bool_t fromInput = kFALSE) const = 0; virtual Double_t GetPointReal(const Int_t *ipoint, Bool_t fromInput = kFALSE) const = 0; virtual void GetPointComplex(Int_t ipoint, Double_t &re, Double_t &im, Bool_t fromInput=kFALSE) const = 0; virtual void GetPointComplex(const Int_t *ipoint, Double_t &re, Double_t &im, Bool_t fromInput=kFALSE) const = 0; virtual Double_t* GetPointsReal(Bool_t fromInput=kFALSE) const = 0; virtual void GetPointsComplex(Double_t *re, Double_t *im, Bool_t fromInput = kFALSE) const = 0; virtual void GetPointsComplex(Double_t *data, Bool_t fromInput = kFALSE) const = 0; virtual void SetPoint(Int_t ipoint, Double_t re, Double_t im = 0) = 0; virtual void SetPoint(const Int_t *ipoint, Double_t re, Double_t im = 0) = 0; virtual void SetPoints(const Double_t *data) = 0; virtual void SetPointComplex(Int_t ipoint, TComplex &c) = 0; virtual void SetPointsComplex(const Double_t *re, const Double_t *im) =0; virtual void Transform() = 0; static TVirtualFFT* FFT(Int_t ndim, Int_t *n, Option_t *option); static TVirtualFFT* SineCosine(Int_t ndim, Int_t *n, Int_t *r2rkind, Option_t *option); static TVirtualFFT* GetCurrentTransform(); static void SetTransform(TVirtualFFT *fft); static const char* GetDefaultFFT(); static void SetDefaultFFT(const char *name =""); ClassDef(TVirtualFFT, 0); //abstract interface for FFT calculations }; #endif