kopia lustrzana https://github.com/Dsplib/libdspl-2.0
186 wiersze
5.8 KiB
C
186 wiersze
5.8 KiB
C
/*
|
||
* Copyright (c) 2015-2019 Sergey Bakhurin
|
||
* Digital Signal Processing Library [http://dsplib.org]
|
||
*
|
||
* This file is part of libdspl-2.0.
|
||
*
|
||
* is free software: you can redistribute it and/or modify
|
||
* it under the terms of the GNU Lesser General Public License as published by
|
||
* the Free Software Foundation, either version 3 of the License, or
|
||
* (at your option) any later version.
|
||
*
|
||
* DSPL is distributed in the hope that it will be useful,
|
||
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
||
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
||
* GNU General Public License for more details.
|
||
*
|
||
* You should have received a copy of the GNU Lesser General Public License
|
||
* along with Foobar. If not, see <http://www.gnu.org/licenses/>.
|
||
*/
|
||
|
||
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
#include <math.h>
|
||
#include "dspl.h"
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
|
||
#ifdef DOXYGEN_ENGLISH
|
||
/*! ****************************************************************************
|
||
\ingroup DFT_GROUP
|
||
\fn int fourier_series_rec(double* w, complex_t* s, int nw,
|
||
double* t, int nt, complex_t* y)
|
||
\brief Time signal reconstruction from Fourier series coefficients.
|
||
|
||
Function reconstructs the time signal:
|
||
|
||
\f[
|
||
s(t) = \sum\limits_{n = 0}^{n_{\omega}-1} S(\omega_n) \exp(j\omega_n t)
|
||
\f]
|
||
|
||
\param[in] w
|
||
Pointer to the Fourier series spectrum frequency vector \f$\omega_n\f$. \n
|
||
Vector size is `[nw x 1]`. \n
|
||
\n
|
||
|
||
\param[in] s
|
||
Pointer to the Fourier series coefficients vector \f$S(\omega_n)\f$. \n
|
||
Vector size is `[nw x 1]`. \n
|
||
\n
|
||
|
||
|
||
\param[in] nw
|
||
Number of Fourier series coefficients. \n
|
||
This value must be positive. \n
|
||
\n
|
||
|
||
\param[in] t
|
||
Pointer to the reconstructed signal time vector. \n
|
||
Vector size is `[nt x 1]`. \n
|
||
\n
|
||
|
||
\param[in] nt
|
||
Size of time vector and reconstructed signal vector . \n
|
||
\n
|
||
|
||
\param[out] y
|
||
Pointer to the reconstructed signal vector. \n
|
||
Vector size is `[nt x 1]`. \n
|
||
Memory must be allocated. \n
|
||
\n
|
||
|
||
\return
|
||
`RES_OK` if function is calculated successfully. \n
|
||
Else \ref ERROR_CODE_GROUP "code error".
|
||
|
||
\note
|
||
The output reconstructed signal is generally complex.
|
||
However, subject to the symmetry properties of the vectors `w` and` s`
|
||
with respect to zero frequency we get the imaginary part of the vector `y`
|
||
at the EPS level. The negligible imaginary part in this case
|
||
can be ignored.
|
||
\n
|
||
|
||
\author Sergey Bakhurin www.dsplib.org
|
||
***************************************************************************** */
|
||
#endif
|
||
#ifdef DOXYGEN_RUSSIAN
|
||
/*! ****************************************************************************
|
||
\ingroup DFT_GROUP
|
||
\fn int fourier_series_rec(double* w, complex_t* s, int nw,
|
||
double* t, int nt, complex_t* y)
|
||
\brief Восстановление сигнала при усечении ряда Фурье
|
||
|
||
Функция рассчитывает восстановленный сигнал при усечении ряда Фурье:
|
||
|
||
\f[
|
||
s(t) = \sum\limits_{n = 0}^{n_{\omega}-1} S(\omega_n) \exp(j\omega_n t)
|
||
\f]
|
||
|
||
\param[in] w
|
||
Указатель на массив частот \f$\omega_n\f$ усеченного ряда Фурье. \n
|
||
Размер вектора `[nw x 1]`. \n
|
||
Память должна быть выделена и заполнена. \n
|
||
\n
|
||
|
||
\param[in] s
|
||
Указатель на массив значений спектра \f$S(\omega_n)\f$. \n
|
||
Размер вектора `[nw x 1]`. \n
|
||
Память должна быть выделена и заполнена. \n
|
||
\n
|
||
|
||
|
||
\param[in] nw
|
||
Количество членов усеченного ряда Фурье. \n
|
||
Значение должно быть положительным. \n
|
||
\n
|
||
|
||
\param[in] t
|
||
Указатель на массив временных отсчетов восстановленного сигнала. \n
|
||
Размер вектора `[nt x 1]`. \n
|
||
Память должна быть выделена и заполнена. \n
|
||
\n
|
||
|
||
\param[in] nt
|
||
Размер вектора времени и восстановленного сигнала. \n
|
||
\n
|
||
|
||
\param[out] y
|
||
Указатель на массив восстановленного сигнала. \n
|
||
Размер вектора `[nt x 1]`. \n
|
||
Память должна быть выделена. \n
|
||
\n
|
||
|
||
\return
|
||
`RES_OK` --- восстановление сигнала прошло успешно. \n
|
||
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
||
|
||
\note
|
||
Выходной восстановленный сигнал в общем случае является комплексным.
|
||
Однако при соблюдении свойств симметрии векторов `w` и `s` относительно
|
||
нулевой частоты получим мнимую часть элементов вектора `y` на уровне ошибок
|
||
округления числа с двойной точностью. Ничтожно малую мнимую часть в этом случае
|
||
можно игнорировать.
|
||
\n
|
||
|
||
\author Бахурин Сергей www.dsplib.org
|
||
***************************************************************************** */
|
||
#endif
|
||
int DSPL_API fourier_series_rec(double* w, complex_t* s, int nw,
|
||
double* t, int nt, complex_t* y)
|
||
{
|
||
int k, m;
|
||
complex_t e;
|
||
|
||
if(!t || !s || !w || !y)
|
||
return ERROR_PTR;
|
||
if(nt<1 || nw < 1)
|
||
return ERROR_SIZE;
|
||
|
||
memset(y, 0, nt*sizeof(complex_t));
|
||
|
||
|
||
for(k = 0; k < nw; k++)
|
||
{
|
||
for(m = 0; m < nt; m++)
|
||
{
|
||
RE(e) = cos(w[k] * t[m]);
|
||
IM(e) = sin(w[k] * t[m]);
|
||
|
||
RE(y[m]) += CMRE(s[k], e);
|
||
IM(y[m]) += CMIM(s[k], e);
|
||
}
|
||
}
|
||
return RES_OK;
|
||
}
|
||
|