kopia lustrzana https://github.com/Dsplib/libdspl-2.0
308 wiersze
9.4 KiB
C
308 wiersze
9.4 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 <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "dspl.h"
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#ifdef DOXYGEN_ENGLISH
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/*! ****************************************************************************
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\ingroup IIR_FILTER_DESIGN_GROUP
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\fn int ellip_ap_zp(int ord, double rp, double rs, complex_t* z, int* nz,
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complex_t* p, int* np)
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\brief
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Function calculates arrays of zeros and poles for analog normlized lowpass
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elliptic filter transfer function \f$ H(s) \f$ order `ord` .
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\param[in] ord
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Filter order. \n
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Number of zeros and poles of filter can be less or equal `ord`. \n
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\n
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\param[in] rp
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Magnitude ripple in passband (dB). \n
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This parameter sets maximum filter distortion from 0 to 1 rad/s frequency. \n
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Parameter must be positive. \n
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\n
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\param[in] rs
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Suppression level in stopband (dB). \n
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This parameter sets filter suppression
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for \f$\omega \geq 1\f$ rad/s frequency. \n
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Parameter must be positive. \n
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\n
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\param[out] z
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Pointer to the \f$ H(s) \f$ zeros array. \n
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Maximum vector size is `[ord x 1]`. \n
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Memory must be allocated for maximum vector size. \n
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\n
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\param[out] nz
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Pointer to the variable which keep number of finite zeros \f$ H(s) \f$. \n
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Number of finite zeros which was calculated and saved in vector `z`. \n
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Pointer cannot be `NULL`. \n
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\n
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\param[out] p
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Pointer to the \f$ H(s) \f$ poles array. \n
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Maximum vector size is `[ord x 1]`. \n
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Memory must be allocated for maximum vector size. \n
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\n
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\param[out] np
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Pointer to the variable which keep number of
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calculated poles of \f$ H(s) \f$. \n
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Pointer cannot be `NULL`. \n
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\n
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\return
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`RES_OK` if zeros and poles is calculated successfully. \n
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Else \ref ERROR_CODE_GROUP "code error".
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\n
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Example of normalized elliptic lowpass filter zeros and poles calculation:
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\include ellip_ap_zp_test.c
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Result:
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\verbatim
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Elliptic filter zeros: 6
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z[ 0] = 0.000 +1.053 j
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z[ 1] = 0.000 -1.053 j
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z[ 2] = 0.000 +1.136 j
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z[ 3] = 0.000 -1.136 j
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z[ 4] = 0.000 +1.626 j
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z[ 5] = 0.000 -1.626 j
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Elliptic filter poles: 7
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p[ 0] = -0.358 +0.000 j
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p[ 1] = -0.011 +1.000 j
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p[ 2] = -0.011 -1.000 j
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p[ 3] = -0.060 +0.940 j
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p[ 4] = -0.060 -0.940 j
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p[ 5] = -0.206 +0.689 j
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p[ 6] = -0.206 -0.689 j
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\endverbatim
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\n
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In `dat` folder will be created `ellip_ap_z.txt` and
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`ellip_ap_z.txt` files which keeps zeros and poles vectors. \n
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In addition, GNUPLOT will build the following graphs
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from data stored in the files:
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\image html ellip_ap_zp_test.png
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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 IIR_FILTER_DESIGN_GROUP
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\fn int ellip_ap_zp(int ord, double rp, double rs, complex_t* z, int* nz,
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complex_t* p, int* np)
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\brief
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Расчет массивов нулей и полюсов передаточной функции \f$ H(s) \f$
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аналогового нормированного эллиптического ФНЧ.
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\param[in] ord
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Порядок фильтра. \n
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\n
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\param[in] rp
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Неравномерность АЧХ в полосе пропускания (дБ). \n
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Параметр задает уровень искажений в полосе от 0 до 1 рад/с. \n
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Значение должно быть положительным. \n
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\n
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\param[in] rs
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Уровень подавления АЧХ в полосе загражения (дБ). \n
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Параметр задает уровень подавления сигнала в полосе частот от 1 рад/с и выше. \n
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Значение должно быть положительным. \n
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\n
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\param[out] z
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Указатель на массив комплексных нулей передаточной функции \f$H(s)\f$. \n
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Максимальный размер вектора вектора `[ord x 1]`. \n
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Память должна быть выделена. \n
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\n
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\param[out] nz
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Указатель на переменную количества нулей передаточной функции \f$H(s)\f$. \n
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По данному указателю будет записано количество нулей фильтра, которые были
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рассчитаны и помещены в вектор `z`. \n
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Память должна быть выделена. \n
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\n
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\param[out] p
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Указатель на массив комплексных полюсов передаточной функции \f$H(s)\f$. \n
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Максимальный размер вектора вектора `[ord x 1]`. \n
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Память должна быть выделена. \n
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\n
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\param[out] np
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Указатель на переменную количества полюсов передаточной функции \f$H(s)\f$. \n
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По данному указателю будет записано количество нулей
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фильтра, которые были
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рассчитаны и помещены в вектор `p`. \n
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Память должна быть выделена. \n
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\n
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\return
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`RES_OK` --- массивы нулей и полюсов рассчитаны успешно. \n
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В противном случае \ref ERROR_CODE_GROUP "код ошибки". \n
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Пример использования функции `cheby2_ap_zp`:
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Пример программы рассчета нулей и полюсов нормированного
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эллиптического ФНЧ :
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\include ellip_ap_zp_test.c
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Результат выполнения программы:
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\verbatim
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Elliptic filter zeros: 6
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z[ 0] = 0.000 +1.053 j
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z[ 1] = 0.000 -1.053 j
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z[ 2] = 0.000 +1.136 j
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z[ 3] = 0.000 -1.136 j
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z[ 4] = 0.000 +1.626 j
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z[ 5] = 0.000 -1.626 j
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Elliptic filter poles: 7
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p[ 0] = -0.358 +0.000 j
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p[ 1] = -0.011 +1.000 j
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p[ 2] = -0.011 -1.000 j
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p[ 3] = -0.060 +0.940 j
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p[ 4] = -0.060 -0.940 j
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p[ 5] = -0.206 +0.689 j
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p[ 6] = -0.206 -0.689 j
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\endverbatim
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\n
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В каталоге `dat` будет создан файлы `ellip_ap_z.txt` и `ellip_ap_z.txt`,
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хранящие наборы нулей и полюсов на комплексной плоскости. \n
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Пакет GNUPLOT произведет построение карты полюсов по
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сохранненным в `dat/ellip_ap_z.txt` и `dat/ellip_ap_p.txt` данным:
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\image html ellip_ap_zp_test.png
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\author
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Бахурин Сергей
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www.dsplib.org
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***************************************************************************** */
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#endif
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int DSPL_API ellip_ap_zp(int ord, double rp, double rs,
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complex_t* z, int* nz, complex_t* p, int* np)
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{
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double es, ep;
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int L, r, n, res;
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int iz, ip;
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double ke, k, u, t;
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complex_t tc, v0, jv0;
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if(rp < 0 || rp == 0)
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return ERROR_FILTER_RP;
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if(rs < 0 || rs == 0)
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return ERROR_FILTER_RS;
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if(ord < 1)
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return ERROR_FILTER_ORD;
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if(!z || !p || !nz || !np)
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return ERROR_PTR;
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es = sqrt(pow(10.0, rs*0.1) - 1.0);
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ep = sqrt(pow(10.0, rp*0.1) - 1.0);
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ke = ep / es;
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r = ord % 2;
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L = (int)((ord-r)/2);
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res = ellip_modulareq(rp, rs, ord, &k);
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if(res != RES_OK)
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return res;
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// v0
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RE(tc) = 0.0;
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IM(tc) = 1.0 / ep;
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ellip_asn_cmplx(&tc, 1, ke, &v0);
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t = RE(v0);
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RE(v0) = IM(v0) / (double)ord;
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IM(v0) = -t / (double)ord;
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RE(jv0) = -IM(v0);
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IM(jv0) = RE(v0);
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iz = ip = 0;
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if(r)
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{
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res = ellip_sn_cmplx(&jv0, 1, k, &tc);
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if(res != RES_OK)
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return res;
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RE(p[0]) = -IM(tc);
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IM(p[0]) = RE(tc);
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ip = 1;
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}
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for(n = 0; n < L; n++)
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{
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u = (double)(2 * n + 1)/(double)ord;
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res = ellip_cd(& u, 1, k, &t);
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if(res != RES_OK)
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return res;
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RE(z[iz]) = RE(z[iz+1]) = 0.0;
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IM(z[iz]) = 1.0/(k*t);
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IM(z[iz+1]) = -1.0/(k*t);
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iz+=2;
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RE(tc) = u - RE(jv0);
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IM(tc) = - IM(jv0);
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res = ellip_cd_cmplx(&tc, 1, k, p+ip+1);
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if(res != RES_OK)
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return res;
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RE(p[ip]) = -IM(p[ip+1]);
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IM(p[ip]) = RE(p[ip+1]);
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RE(p[ip+1]) = RE(p[ip]);
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IM(p[ip+1]) = -IM(p[ip]);
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ip+=2;
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}
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*nz = iz;
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*np = ip;
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return RES_OK;
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}
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