lib/qtsFFT.h

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#ifndef qtsFFT_H
#define qtsFFT_H

#include "PlotLine.h"


class FFTReal;

class qtsFFT
{
    
public:

    qtsFFT(long n);
        ~qtsFFT();

    PlotLine * do_FFTqts(PlotLine *r);
    PlotLine * do_iFFTqts(PlotLine *f);
    
private:

    int length;

    double * fftReal;       // qtsFFT arrays
    double * fftFreq;
    
//
// FFTReal by Laurent de Soras
// Modified to nested class for inclusion in this module
//      -- jim nolen jnolen1@mindspring.com, 29 Nov 2004
//
    
// --- nested Class FFTReal ----
    class FFTReal
    {
                public:

                        /* Change this typedef to use a different floating point type in your FFTs
                        (i.e. float, double or long double). */
                        typedef double  flt_t;
                        
                        explicit        FFTReal (const long length);
                                                ~FFTReal ();
                        void            do_fft (flt_t f [], const flt_t x []) const;
                        void            do_ifft (const flt_t f [], flt_t x []) const;
                        void            rescale (flt_t x []) const;

                private:

                        /* Bit-reversed look-up table nested class */
                        class BitReversedLUT
                        {
                                public:
                                
                                        explicit                BitReversedLUT (const int nbr_bits);
                                                                        ~BitReversedLUT ();
                                        const long *    get_ptr () const
                                        {
                                        return (_ptr);
                                        }
                                private:
                                        long *                  _ptr;
                        };

                        /* Trigonometric look-up table nested class */
                        class   TrigoLUT
                        {
                                public:

                                        explicit                TrigoLUT (const int nbr_bits);
                                                                        ~TrigoLUT ();
                                        const flt_t     *       get_ptr (const int level) const
                                        {
                                                return (_ptr + (1L << (level - 1)) - 4);
                                        };
                        private:
                                flt_t   *                       _ptr;
                        };

                const long              _length;
                const int               _nbr_bits;
                const BitReversedLUT    _bit_rev_lut;
                const TrigoLUT  _trigo_lut;
                const flt_t             _sqrt2_2;
                flt_t *                 _buffer_ptr;
            
                };
                
        const FFTReal _ftt_Real;
    
};

#endif

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