kopia lustrzana https://github.com/Dsplib/libdspl-2.0
202 wiersze
6.3 KiB
C
202 wiersze
6.3 KiB
C
/*
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* Copyright (c) 2015-2019 Sergey Bakhurin
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* Digital Signal Processing Library [http://dsplib.org]
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*
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* This file is part of libdspl-2.0.
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*
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* is free software: you can redistribute it and/or modify
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* it under the terms of the GNU Lesser General Public License as published by
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* the Free Software Foundation, either version 3 of the License, or
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* (at your option) any later version.
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*
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* DSPL is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public License
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* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#include <float.h>
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#include "dspl.h"
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#include "dspl_internal.h"
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#ifdef DOXYGEN_ENGLISH
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/*! ****************************************************************************
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\ingroup DFT_GROUP
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\fn int fft_cmplx(complex_t* x, int n, fft_t* pfft, complex_t* y)
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\brief Fast Fourier transform for the complex vector.
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Function calculated \f$ n \f$-points FFT for the complex vector
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\f$ x(m) \f$, \f$ m = 0 \ldots n-1 \f$. \n
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\f[
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Y(k) = \sum_{m = 0}^{n-1} x(m) \exp \left( -j \frac{2\pi}{n} m k \right),
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\f]
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here \f$ k = 0 \ldots n-1 \f$.
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\param[in] x
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Pointer to the input complex vector \f$x(m)\f$,
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\f$ m = 0 \ldots n-1 \f$. \n
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Vector size is `[n x 1]`. \n \n
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\param[in] n
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FFT size \f$n\f$. \n
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FFT size can be composite:
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\f$n = n_0 \times n_1 \times n_2 \times \ldots \times n_p \times m\f$,
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here \f$n_i = 2,3,5,7\f$, а \f$m \f$ --
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simple number less than 46340
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(see \ref fft_create function). \n \n
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\param[in] pfft
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Pointer to the `fft_t` object. \n
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This pointer cannot be `NULL`. \n
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Structure \ref fft_t should be previously once
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filled with the \ref fft_create function, and the memory should be
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cleared before exiting by the \ref fft_free function. \n \n
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\param[out] y
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Pointer to the FFT result complex vector \f$Y(k)\f$,
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\f$ k = 0 \ldots n-1 \f$. \n
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Vector size is `[n x 1]`. \n
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Memory must be allocated. \n \n
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\return
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`RES_OK` if FFT is calculated successfully. \n
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Else \ref ERROR_CODE_GROUP "code error".
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Example:
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\include fft_cmplx_test.c
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Result:
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\verbatim
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y[ 0] = -0.517 0.686
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y[ 1] = -0.943 0.879
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y[ 2] = -2.299 1.492
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y[ 3] = 16.078 -6.820
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y[ 4] = 2.040 -0.470
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y[ 5] = 1.130 -0.059
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y[ 6] = 0.786 0.097
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y[ 7] = 0.596 0.183
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y[ 8] = 0.470 0.240
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y[ 9] = 0.375 0.283
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y[10] = 0.297 0.318
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y[11] = 0.227 0.350
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y[12] = 0.161 0.380
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y[13] = 0.094 0.410
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y[14] = 0.023 0.442
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y[15] = -0.059 0.479
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y[16] = -0.161 0.525
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y[17] = -0.300 0.588
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\endverbatim
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\author Sergey Bakhurin www.dsplib.org
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***************************************************************************** */
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#endif
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#ifdef DOXYGEN_RUSSIAN
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/*! ****************************************************************************
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\ingroup DFT_GROUP
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\fn int fft_cmplx(complex_t* x, int n, fft_t* pfft, complex_t* y)
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\brief Быстрое преобразование Фурье комплексного сигнала
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Функция рассчитывает \f$ n \f$-точечное быстрое преобразование Фурье
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комплексного сигнала \f$ x(m) \f$, \f$ m = 0 \ldots n-1 \f$. \n
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\f[
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Y(k) = \sum_{m = 0}^{n-1} x(m) \exp \left( -j \frac{2\pi}{n} m k \right),
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\f]
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где \f$ k = 0 \ldots n-1 \f$.
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Для расчета используется алгоритм БПФ составной длины.
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\param[in] x
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Указатель на вектор комплексного
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входного сигнала \f$x(m)\f$, \f$ m = 0 \ldots n-1 \f$. \n
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Размер вектора `[n x 1]`. \n \n
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\param[in] n
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Размер БПФ \f$n\f$. \n
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Размер БПФ может быть составным вида
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\f$ n = n_0 \times n_1 \times n_2 \times n_3 \times \ldots
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\times n_p \times m \f$,
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где \f$n_i = 2,3,5,7\f$, а \f$m \f$ --
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произвольный простой множитель не превосходящий 46340
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(см. описание функции \ref fft_create). \n \n
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\param[in] pfft
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Указатель на структуру `fft_t`. \n
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Указатель не должен быть `NULL`. \n
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Структура \ref fft_t должна быть предварительно однократно
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заполнена функцией \ref fft_create, и память должна быть
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очищена перед выходом функцией \ref fft_free. \n \n
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\param[out] y
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Указатель на комплексный вектор
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результата БПФ \f$Y(k)\f$,
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\f$ k = 0 \ldots n-1 \f$.
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Размер вектора `[n x 1]`. \n
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Память должна быть выделена. \n \n
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\return
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`RES_OK` если расчет произведен успешно. \n
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В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n \n
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Пример использования функции `fft`:
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\include fft_cmplx_test.c
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Результат работы программы:
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\verbatim
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y[ 0] = -0.517 0.686
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y[ 1] = -0.943 0.879
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y[ 2] = -2.299 1.492
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y[ 3] = 16.078 -6.820
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y[ 4] = 2.040 -0.470
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y[ 5] = 1.130 -0.059
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y[ 6] = 0.786 0.097
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y[ 7] = 0.596 0.183
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y[ 8] = 0.470 0.240
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y[ 9] = 0.375 0.283
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y[10] = 0.297 0.318
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y[11] = 0.227 0.350
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y[12] = 0.161 0.380
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y[13] = 0.094 0.410
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y[14] = 0.023 0.442
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y[15] = -0.059 0.479
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y[16] = -0.161 0.525
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y[17] = -0.300 0.588
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\endverbatim
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\author Бахурин Сергей www.dsplib.org
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***************************************************************************** */
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#endif
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int DSPL_API fft_cmplx(complex_t* x, int n, fft_t* pfft, complex_t* y)
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{
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int err;
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if(!x || !pfft || !y)
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return ERROR_PTR;
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if(n<1)
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return ERROR_SIZE;
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err = fft_create(pfft, n);
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if(err != RES_OK)
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return err;
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memcpy(pfft->t1, x, n*sizeof(complex_t));
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return fft_krn(pfft->t1, y, pfft, n, 0);
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}
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