/* * This material contains proprietary software of Entropic Speech, Inc. * Any reproduction, distribution, or publication without the prior * written permission of Entropic Speech, Inc. is strictly prohibited. * Any public distribution of copies of this work authorized in writing by * Entropic Speech, Inc. must bear the notice * *    "Copyright (c) 1986, 1987 Entropic Speech, Inc.; All rights reserved" * *//*--------------------------------------------------------------+|								||  get_arspect -- compute max-entropy spectrum from residual 	||                 power and filter coefficients			||								||  by Shankar Narayan, EPI; enhancements by Rod Johnson.	||								||  Module:  getarspec.c						||  								||  Accepts an array c of analysis filter coefficients of given	||  order, a residual energy renergy, a sampling frequency	||  sampfreq, and a number n of frequencies.  Computes an array	||  y of (log) spectral power densities in db at n equispaced	||  frequencies.  Calls getfft to compute a discrete Fourier	||  transform.							||								|  +--------------------------------------------------------------*/#ifdef SCCS    static char *sccs_id  = "@(#)getarspec.c	1.2	6/25/87";#endif#include <stdio.h>#include "getarspec.h"typedef struct complex {    double  real;    double  imag;}       COMPLEX ;double  log10(), sqrt();extern  debug_level;get_arspect(c, order, renergy, sampfreq, y, n)    int     order, sampfreq, n;    float   c[], renergy, y[];{    double  t;    int     i;    static COMPLEX temp[DFTMAX];  /* Size defined in getarspec.h */    int     dftsize = 2*(n-1);    c[0] = -1.0;    if (debug_level)        fprintf(stderr, "Filter coefficients:\n");    for (i = 0; i < dftsize; i++)    {	temp[i].real = (i <= order) ? c[i] : 0.0;	temp[i].imag = 0.0;        if (debug_level)	{	    fprintf(stderr, "%lf\t", temp[i].real);            if (i%5 == 4 || i == dftsize - 1)                fprintf(stderr, "\n");        }    }    get_fft_comp(temp, dftsize);    for (i = 0; i < n; i++)    {	t = temp[i].real * temp[i].real	    + temp[i].imag * temp[i].imag;	if (t < .0000001)	    t = 0.0000001;	y[i] = 10.0 * log10((2.0*renergy) / (t*sampfreq));    }}