ivfilt.c File Reference

#include "f2c.h"

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Functions
int	ivfilt_ (real *lpbuf, real *ivbuf, integer *len, integer *nsamp, real *ivrc)

Function Documentation

ivfilt_()

int ivfilt_	(	real *	lpbuf,
		real *	ivbuf,
		integer *	len,
		integer *	nsamp,
		real *	ivrc
	)

Definition at line 89 of file ivfilt.c.

References len().

Referenced by analys_().

{
 /* System generated locals */
 integer i__1;

 /* Local variables */
 integer i__, j, k;
 real r__[3], pc1, pc2;

/* Arguments */
/* Local variables that need not be saved */
/* Local state */
/* None */
/* Calculate Autocorrelations */
 /* Parameter adjustments */
 --ivbuf;
 --lpbuf;
 --ivrc;

 /* Function Body */
 for (i__ = 1; i__ <= 3; ++i__) {
 r__[i__ - 1] = 0.f;
 k = (i__ - 1) << 2;
 i__1 = *len;
 for (j = (i__ << 2) + *len - *nsamp; j <= i__1; j += 2) {
 r__[i__ - 1] += lpbuf[j] * lpbuf[j - k];
 }
 }
/* Calculate predictor coefficients */
 pc1 = 0.f;
 pc2 = 0.f;
 ivrc[1] = 0.f;
 ivrc[2] = 0.f;
 if (r__[0] > 1e-10f) {
 ivrc[1] = r__[1] / r__[0];
 ivrc[2] = (r__[2] - ivrc[1] * r__[1]) / (r__[0] - ivrc[1] * r__[1]);
 pc1 = ivrc[1] - ivrc[1] * ivrc[2];
 pc2 = ivrc[2];
 }
/* Inverse filter LPBUF into IVBUF */
 i__1 = *len;
 for (i__ = *len + 1 - *nsamp; i__ <= i__1; ++i__) {
 ivbuf[i__] = lpbuf[i__] - pc1 * lpbuf[i__ - 4] - pc2 * lpbuf[i__ - 8];
 }
 return 0;
} /* ivfilt_ */