kopia lustrzana https://github.com/Dsplib/libdspl-2.0
205 wiersze
7.0 KiB
C
205 wiersze
7.0 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 <stdio.h>
|
||
#include <stdlib.h>
|
||
#include <string.h>
|
||
#include "dspl.h"
|
||
|
||
|
||
|
||
|
||
#ifdef DOXYGEN_ENGLISH
|
||
/*! ****************************************************************************
|
||
\ingroup IIR_FILTER_DESIGN_GROUP
|
||
\fn int filter_zp2ab(complex_t *z, int nz, complex_t *p, int np, int ord,
|
||
double* b, double* a)
|
||
\brief
|
||
Function recalculates complex zeros and poles of transfer function \f$ H(s) \f$
|
||
to the coefficients of \f$ H(s) \f$ numerator and denominator polynomials.
|
||
|
||
Transfer function can we described as:
|
||
\f[
|
||
H(s) =
|
||
\frac{\sum\limits_{n = 0}^{N_z} b_n s^n}{\sum\limits_{m = 0}^{N_p} a_m s^m} =
|
||
\frac{\prod\limits_{n = 0}^{N_z}(s-z_n)}{\prod\limits_{m = 0}^{N_p} (s-p_m)}
|
||
\f]
|
||
|
||
\param[in] z
|
||
Pointer to the vector of transfer function zeros. \n
|
||
Vector size is `[nz x 1]`. \n
|
||
Pointer can be `NULL` if filter has no finite zeros (`nz=0`). \n
|
||
\n
|
||
|
||
\param[in] nz
|
||
Number of fitite zeros (can be zero). \n
|
||
\n
|
||
|
||
\param[in] p
|
||
Pointer to the vector of transfer function poles. \n
|
||
Vector size is `[np x 1]`. \n
|
||
This pointer cannot be `NULL`. \n
|
||
\n
|
||
|
||
\param[in] np
|
||
Size of vector of transfer function poles (`p` vector size). \n
|
||
\n
|
||
|
||
\param[in] ord
|
||
Filter order. \n
|
||
Number of \f$H(s)\f$ numerator and denominator coefficients equals `ord+1`. \n
|
||
\n
|
||
|
||
\param[out] b
|
||
Pointer to the vector of transfer function \f$H(s)\f$
|
||
numerator coefficient. \n
|
||
Vector size is `[ord+1 x 1]`. \n
|
||
Memory must be allocated. \n
|
||
\n
|
||
|
||
\param[out] a
|
||
Pointer to the vector of transfer function \f$H(s)\f$
|
||
denominator coefficient. \n
|
||
Vector size is `[ord+1 x 1]`. \n
|
||
Memory must be allocated. \n
|
||
\n
|
||
|
||
\return
|
||
`RES_OK` if filter coefficients is calculated successfully. \n
|
||
Else \ref ERROR_CODE_GROUP "code error".
|
||
\n
|
||
|
||
\note
|
||
Function calculates real `b` and `a` coefficients of \f$H(s)\f$.
|
||
It means that zeros and poles vectors must have real values or conjugate pairs
|
||
to get zeros image part of `b` and `a` coefficients. This function ignores
|
||
image part of `b` and `a` coeeffitients if the requirements for zeros
|
||
and poles are not fulfilled.
|
||
|
||
\author Sergey Bakhurin www.dsplib.org
|
||
***************************************************************************** */
|
||
#endif
|
||
#ifdef DOXYGEN_RUSSIAN
|
||
/*! ****************************************************************************
|
||
\ingroup IIR_FILTER_DESIGN_GROUP
|
||
\fn int filter_zp2ab(complex_t *z, int nz, complex_t *p, int np, int ord,
|
||
double* b, double* a)
|
||
\brief Функция пересчета нулей и полюсов аналогового фильтра в коэффициенты
|
||
передаточной характеристики \f$ H(s) \f$
|
||
|
||
\f[
|
||
H(s) =
|
||
\frac{\sum_{n = 0}^{N_z} b_n \cdot s^n}{\sum_{m = 0}^{N_p} a_m \cdot s^m} =
|
||
\frac{\prod_{n = 0}^{N_z}(s-z_n)}{\prod_{m = 0}^{N_p} (s-p_m)}
|
||
\f]
|
||
|
||
\param[in] z
|
||
Указатель на массив нулей передаточной характеристики. \n
|
||
Размер вектора `[nz x 1]`. \n
|
||
Указатель может быть `NULL` если фильтр не имеет конечных нулей (`nz=0`). \n
|
||
\n
|
||
|
||
\param[in] nz
|
||
Размер вектора нулей передаточной характеристики (может быть равен 0). \n
|
||
\n
|
||
|
||
\param[in] p
|
||
Указатель на массив полюсов передаточной характеристики. \n
|
||
Размер вектора `[np x 1]`. \n
|
||
Указатель не может быть `NULL`. \n
|
||
Память должна быть выделена. \n
|
||
\n
|
||
|
||
\param[in] np
|
||
Размер вектора полюсов передаточной характеристики (не может быть равен 0). \n
|
||
\n
|
||
|
||
\param[in] ord
|
||
Порядок фильтра для которого рассчитаны нули и полюса. \n
|
||
Количество коэффициентов числителя и знаменателя
|
||
передаточной функции \f$H(s)\f$ равно `ord+1`. \n \n
|
||
|
||
\param[out] b
|
||
Указатель на вектор коэффициентов числителя передаточной функции \f$H(s)\f$. \n
|
||
Размер вектора `[ord+1 x 1]`. \n
|
||
Память должна быть выделена. \n
|
||
\n
|
||
|
||
\param[out] a
|
||
Указатель на вектор коэффициентов знаменателя
|
||
передаточной функции \f$H(s)\f$. \n
|
||
Размер вектора `[ord+1 x 1]`. \n
|
||
Память должна быть выделена. \n
|
||
\n
|
||
|
||
\return
|
||
`RES_OK` --- пересчет произведен успешно. \n
|
||
В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
|
||
|
||
\note
|
||
Функция возвращает вещественные значения коэффициентов `b` и `a`
|
||
передаточной функции. Это означает, что вектора нулей и полюсов
|
||
должны хранить вещественные значения или комплексно-сопряженные пары
|
||
нулей и полюсов, потому что мнимая часть коэффициентов `b` и `a`
|
||
игнорируется и не сохраняется.
|
||
|
||
\author
|
||
Бахурин Сергей
|
||
www.dsplib.org
|
||
***************************************************************************** */
|
||
#endif
|
||
int DSPL_API filter_zp2ab(complex_t* z, int nz, complex_t* p, int np,
|
||
int ord, double* b, double* a)
|
||
{
|
||
complex_t *acc = NULL;
|
||
int res;
|
||
|
||
if(!z || !p || !b || !a)
|
||
return ERROR_PTR;
|
||
if(nz < 0 || np < 0)
|
||
return ERROR_SIZE;
|
||
if(nz > ord || np > ord)
|
||
return ERROR_POLY_ORD;
|
||
|
||
acc = (complex_t*) malloc((ord+1) * sizeof(complex_t));
|
||
res = poly_z2a_cmplx(z, nz, ord, acc);
|
||
if(res != RES_OK)
|
||
goto exit_label;
|
||
|
||
res = cmplx2re(acc, ord+1, b, NULL);
|
||
if(res != RES_OK)
|
||
goto exit_label;
|
||
|
||
res = poly_z2a_cmplx(p, np, ord, acc);
|
||
if(res != RES_OK)
|
||
goto exit_label;
|
||
|
||
res = cmplx2re(acc, ord+1, a, NULL);
|
||
if(res != RES_OK)
|
||
goto exit_label;
|
||
|
||
exit_label:
|
||
if(acc)
|
||
free(acc);
|
||
return res;
|
||
|
||
}
|
||
|