dspl/ellip__ap_8c_source.html

/*

* Copyright (c) 2015-2024 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


#endif

#ifdef DOXYGEN_RUSSIAN


#endif

int DSPL_API ellip_ap(double rp, double rs, int ord, double* b, double* a)

{

    int res;

    complex_t *z = NULL;

    complex_t *p = NULL;

    int nz, np;

    double norm, g0;


    if(rp < 0.0)

        return ERROR_FILTER_RP;

    if(rs < 0.0)

        return ERROR_FILTER_RS;

    if(ord < 1)

        return ERROR_FILTER_ORD;

    if(!a || !b)

        return ERROR_PTR;


    z = (complex_t*) malloc(ord*sizeof(complex_t));

    p = (complex_t*) malloc(ord*sizeof(complex_t));


    res = ellip_ap_zp(ord, rp, rs, z, &nz, p, &np);

    if(res != RES_OK)

        goto exit_label;


    res = filter_zp2ab(z, nz, p, np, ord, b, a);

    if(res != RES_OK)

        goto exit_label;


    g0 = 1.0;

    if(!(ord % 2))

    {

        g0 = 1.0 / pow(10.0, rp*0.05);

    }


    norm = g0 * a[0] / b[0];


    for(nz = 0; nz < ord+1; nz++)

        b[nz]*=norm;


    exit_label:

    if(z)

        free(z);

    if(p)

        free(p);

    return res;

}