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  )

extern

Definition at line 89 of file ivfilt.c.

{
    /* 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_ */

References len().

Referenced by analys_().