Chris@32: /* 
Chris@32:  * Free FFT and convolution (C)
Chris@32:  * 
Chris@32:  * Copyright (c) 2014 Project Nayuki
Chris@32:  * http://www.nayuki.io/page/free-small-fft-in-multiple-languages
Chris@32:  * 
Chris@32:  * (MIT License)
Chris@32:  * Permission is hereby granted, free of charge, to any person obtaining a copy of
Chris@32:  * this software and associated documentation files (the "Software"), to deal in
Chris@32:  * the Software without restriction, including without limitation the rights to
Chris@32:  * use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of
Chris@32:  * the Software, and to permit persons to whom the Software is furnished to do so,
Chris@32:  * subject to the following conditions:
Chris@32:  * - The above copyright notice and this permission notice shall be included in
Chris@32:  *   all copies or substantial portions of the Software.
Chris@32:  * - The Software is provided "as is", without warranty of any kind, express or
Chris@32:  *   implied, including but not limited to the warranties of merchantability,
Chris@32:  *   fitness for a particular purpose and noninfringement. In no event shall the
Chris@32:  *   authors or copyright holders be liable for any claim, damages or other
Chris@32:  *   liability, whether in an action of contract, tort or otherwise, arising from,
Chris@32:  *   out of or in connection with the Software or the use or other dealings in the
Chris@32:  *   Software.
Chris@32:  */
Chris@32: 
Chris@32: 
Chris@32: /* 
Chris@32:  * Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
Chris@32:  * The vector can have any length. This is a wrapper function. Returns 1 (true) if successful, 0 (false) otherwise (out of memory).
Chris@32:  */
Chris@32: int transform(double real[], double imag[], size_t n);
Chris@32: 
Chris@32: /* 
Chris@32:  * Computes the inverse discrete Fourier transform (IDFT) of the given complex vector, storing the result back into the vector.
Chris@32:  * The vector can have any length. This is a wrapper function. This transform does not perform scaling, so the inverse is not a true inverse.
Chris@32:  * Returns 1 (true) if successful, 0 (false) otherwise (out of memory).
Chris@32:  */
Chris@32: int inverse_transform(double real[], double imag[], size_t n);
Chris@32: 
Chris@32: /* 
Chris@32:  * Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
Chris@32:  * The vector's length must be a power of 2. Uses the Cooley-Tukey decimation-in-time radix-2 algorithm.
Chris@32:  * Returns 1 (true) if successful, 0 (false) otherwise (n is not a power of 2, or out of memory).
Chris@32:  */
Chris@32: int transform_radix2(double real[], double imag[], size_t n);
Chris@32: 
Chris@33: /* Test versions with precalculated structures -- this API is
Chris@33:    absolutely not for production use! */
Chris@32: typedef struct {
Chris@32:     double *cos;
Chris@32:     double *sin;
Chris@32:     int levels;
Chris@32: } tables;
Chris@32: 
Chris@32: tables *precalc(size_t n);
Chris@32: void dispose(tables *);
Chris@32: void transform_radix2_precalc(double real[], double imag[], int n, tables *tables);
Chris@32: 
Chris@33: typedef struct {
Chris@33:     float *cos;
Chris@33:     float *sin;
Chris@33:     int levels;
Chris@33: } tables_f;
Chris@33: 
Chris@33: tables_f *precalc_f(size_t n);
Chris@33: void dispose_f(tables_f *);
Chris@33: void transform_radix2_precalc_f(float real[], float imag[], int n, tables_f *tables);
Chris@33: 
Chris@32: /* 
Chris@32:  * Computes the discrete Fourier transform (DFT) of the given complex vector, storing the result back into the vector.
Chris@32:  * The vector can have any length. This requires the convolution function, which in turn requires the radix-2 FFT function.
Chris@32:  * Uses Bluestein's chirp z-transform algorithm. Returns 1 (true) if successful, 0 (false) otherwise (out of memory).
Chris@32:  */
Chris@32: int transform_bluestein(double real[], double imag[], size_t n);
Chris@32: 
Chris@32: /* 
Chris@32:  * Computes the circular convolution of the given real vectors. Each vector's length must be the same.
Chris@32:  * Returns 1 (true) if successful, 0 (false) otherwise (out of memory).
Chris@32:  */
Chris@32: int convolve_real(const double x[], const double y[], double out[], size_t n);
Chris@32: 
Chris@32: /* 
Chris@32:  * Computes the circular convolution of the given complex vectors. Each vector's length must be the same.
Chris@32:  * Returns 1 (true) if successful, 0 (false) otherwise (out of memory).
Chris@32:  */
Chris@32: int convolve_complex(const double xreal[], const double ximag[], const double yreal[], const double yimag[], double outreal[], double outimag[], size_t n);
Chris@32: