covar.3

speech signal process tools

.\" Copyright (c) 1987 Entropic Speech, Inc.; All rights reserved
.\" @(#)covar.3	1.7 30 Apr 1997 ESI
.TH COVAR 3\-ESPSsp 30 Apr 1997
.ds ]W "Entropic Speech, Inc.
.SH NAME
covar \- compute reflection coefficients using covariance method.
.SH SYNOPSIS
.ft B
covar (x, lnt, c, order, rc, pgain, window_flag)
.br
float   x[], c[], rc[], *pgain;
.br
int     order, lnt, window_flag;

.SH DESCRIPTION
.PP
This routine computes the generalized reflection coefficients and the lpc
filter coefficients for the given data using covariance method.
.PP
The covar function takes data of size
.B lnt
in array
.B x[]
as input and computes
.B order
generalized reflection coefficients,
.B rc[1]
to
.B rc[order],
.B
order
lpc filter coefficients,
.B c[1]
to 
.B c[order],
and lpc filter gain,
.B *pgain.
.PP
If the parameter \fBwindow_flag\fP is 0, a rectangular window is
applied to sample data vectors in the computation of the sample covariance
matrix.  If 
.B
window_flag is non-zero, a triangular window is applied.
.PP
For a more general approach (which also serves as a cover function
for \fIcovar\fP), see \fIcompute_rc\fP (3\-\s-1ESPS\s+1).  
.SH BUGS
None
.SH SEE ALSO
\fIcompute_rc\fP (3\-\s-1ESPS\s+1)
.SH REFERENCES
[1] L. R. Rabiner and R. W. Shaffer,
.I
Digital Processing of speech signals,
Prentice-Hall, NJ, 1978.
.SH AUTHOR
Shankar Narayan