kopia lustrzana https://github.com/Dsplib/libdspl-2.0
204 wiersze
6.5 KiB
C
204 wiersze
6.5 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 <string.h>
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#include <math.h>
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#include "dspl.h"
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#ifdef DOXYGEN_ENGLISH
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/*! ****************************************************************************
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\ingroup FILTER_ANALYSIS_GROUP
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\fn int freqs(double* b, double* a, int ord, double* w, int n, complex_t *h)
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\brief Analog filter frequency response \f$ H(j \omega) \f$ calculation
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Function calculates analog filter frequency response \f$ H(j \omega)\f$
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corresponds to transfer function \f$ H(s) \f$:
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\f[
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H(s) = \frac {\sum_{k = 0}^{N} b_k s^k}
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{\sum_{m = 0}^{N} a_m s^m},
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\f]
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here \f$ N \f$ - filter order (equals to `ord`).
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\param[in] b
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Pointer to the transfer function \f$ H(s) \f$
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numerator coefficients vector. \n
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Vector size is `[ord+1 x 1]`. \n \n
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\param[in] a
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Pointer to the transfer function \f$ H(s) \f$
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denominator coefficients vector. \n
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Vector size is `[ord+1 x 1]`. \n \n
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\param[in] ord
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Filter order. \n
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Transfer function \f$ H(s) \f$ numerator and denominator
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coefficients number equals `ord+1`. \n \n
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\param[in] w
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Pointer to the angular frequency \f$ \omega \f$ (rad/s),
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which used for frequency response \f$ H(j \omega) \f$ calculation. \n
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Vector size is `[n x 1]`. \n \n
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\param[in] n
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The size of the angular frequency vector `w`. \n \n
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\param[out] h
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Pointer to the frequency response vector \f$ H(j \omega) \f$,
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corresponds to angular frequency `w`. \n
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Vector size is `[n x 1]`. \n
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Memory must be allocated. \n \n
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\return `RES_OK` if frequency response vector is calculated successfully. \n
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Else \ref ERROR_CODE_GROUP "code error".
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\author Sergey Bakhurin www.dsplib.org
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***************************************************************************** */
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#endif
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#ifdef DOXYGEN_RUSSIAN
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/*! ****************************************************************************
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\ingroup FILTER_ANALYSIS_GROUP
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\fn int freqs(double* b, double* a, int ord, double* w, int n, complex_t *h)
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\brief Расчет комплексного коэффициента передачи
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\f$ H(j \omega) \f$ аналогового фильтра.
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Функция рассчитывает значения комплексного коэффициента передачи
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\f$ H(j \omega)\f$ аналогового фильтра, заданного коэффициентами
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передаточной функции \f$ H(s) \f$:
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\f[
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H(s) = \frac {\sum_{k = 0}^{N} b_k s^k}
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{\sum_{m = 0}^{N} a_m s^m},
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\f]
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где \f$ N \f$ - порядок фильтра (параметр `ord`).
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Комплексный коэффициент передачи рассчитывается путем
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подстановки \f$ s = j \omega \f$.
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\param[in] b
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Указатель на вектор коэффициентов числителя
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передаточной функции \f$ H(s) \f$. \n
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Размер вектора `[ord+1 x 1]`. \n \n
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\param[in] a
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Указатель на вектор коэффициентов знаменателя
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передаточной функции \f$ H(s) \f$. \n
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Размер вектора `[ord+1 x 1]`. \n \n
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\param[in] ord
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Порядок фильтра. Количество коэффициентов числителя и
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знаменателя передаточной функции \f$ H(s) \f$
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равно `ord+1`. \n \n
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\param[in] w
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Указатель на вектор значений циклической частоты \f$ \omega \f$ (рад/с),
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для которого будет рассчитан комплексный
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коэффициент передачи \f$ H(j \omega) \f$. \n
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Размер вектора `[n x 1]`. \n \n
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\param[in] n
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Размер вектора циклической частоты `w`. \n \n
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\param[out] h
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Указатель на вектор комплексного коэффициента передачи \f$ H(j \omega) \f$,
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рассчитанного для циклической частоты `w`. \n
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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` Комплексный коэффициент передачи рассчитан успешно. \n
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В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
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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 freqs(double* b, double* a, int ord,
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double* w, int n, complex_t *h)
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{
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complex_t jw;
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complex_t *bc = NULL;
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complex_t *ac = NULL;
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complex_t num, den;
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double mag;
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int k;
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int res;
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if(!b || !a || !w || !h)
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return ERROR_PTR;
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if(ord<0)
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return ERROR_FILTER_ORD;
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if(n<1)
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return ERROR_SIZE;
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RE(jw) = 0.0;
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bc = (complex_t*) malloc((ord+1) * sizeof(complex_t));
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res = re2cmplx(b, ord+1, bc);
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if( res!=RES_OK )
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goto exit_label;
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ac = (complex_t*) malloc((ord+1) * sizeof(complex_t));
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res = re2cmplx(a, ord+1, ac);
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if( res!=RES_OK )
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goto exit_label;
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for(k = 0; k < n; k++)
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{
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IM(jw) = w[k];
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res = polyval_cmplx(bc, ord, &jw, 1, &num);
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if(res != RES_OK)
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goto exit_label;
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res = polyval_cmplx(ac, ord, &jw, 1, &den);
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if(res != RES_OK)
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goto exit_label;
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mag = ABSSQR(den);
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if(mag == 0.0)
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{
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res = ERROR_DIV_ZERO;
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goto exit_label;
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}
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mag = 1.0 / mag;
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RE(h[k]) = CMCONJRE(num, den) * mag;
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IM(h[k]) = CMCONJIM(num, den) * mag;
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}
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res = RES_OK;
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exit_label:
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if(bc)
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free(bc);
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if(ac)
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free(ac);
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return res;
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}
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