kopia lustrzana https://github.com/Dsplib/libdspl-2.0
97 wiersze
2.5 KiB
C
97 wiersze
2.5 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 <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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#endif
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#ifdef DOXYGEN_RUSSIAN
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#endif
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double DSPL_API filter_ws1(int ord, double rp, double rs, int type)
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{
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double es2, ep2, gs2, x, ws;
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if(ord<1 || rp < 0.0 || rs < 0.0)
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return -1.0;
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es2 = pow(10.0, rs*0.1) - 1.0;
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ep2 = pow(10.0, rp*0.1) - 1.0;
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gs2 = 1.0 / (1.0 + es2);
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x = (1.0 - gs2) / (gs2 * ep2);
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switch( type & DSPL_FILTER_APPROX_MASK)
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{
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case DSPL_FILTER_BUTTER:
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ws = pow(x, 0.5 / (double)ord);
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break;
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case DSPL_FILTER_CHEBY1:
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case DSPL_FILTER_CHEBY2:
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x = sqrt(x) + sqrt(x - 1.0);
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x = log(x) / (double)ord;
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ws = 0.5 * (exp(-x) + exp(x));
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break;
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case DSPL_FILTER_ELLIP:
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{
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double k, k1;
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complex_t y, z;
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int res;
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k = sqrt(ep2 / es2);
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res = ellip_modulareq(rp, rs, ord, &k1);
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if(res != RES_OK)
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{
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ws = -1.0;
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break;
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}
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RE(z) = sqrt(x);
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IM(z) = 0.0;
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res = ellip_acd_cmplx(&z, 1, k, &y);
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if(res != RES_OK)
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{
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ws = -1.0;
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break;
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}
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RE(y) /= (double)ord;
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IM(y) /= (double)ord;
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res = ellip_cd_cmplx(&y, 1, k1, &z);
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if(res != RES_OK)
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{
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ws = -1.0;
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break;
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}
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ws = RE(z);
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break;
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}
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default:
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ws = -1.0;
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break;
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}
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return ws;
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}
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