lartorc.3

来自「speech signal process tools」· 3 代码 · 共 93 行

.\" Copyright (c) 1987-1990 Entropic Speech, Inc.
.\" Copyright (c) 1997 Entropic Research Laboratory, Inc. All rights reserved.
.\" @(#)lartorc.3	1.6 18 Apr 1997 ESI/ERL
.ds ]W (c) 1997 Entropic Research Laboratory, Inc.
.TH LAR_TO_RC 3\-ESPSsp 18 Apr 1997
.SH NAME
.nf
lar_to_rc \- convert log area ratio to reflection coefficient
rc_to_lar \- convert reflection coefficient to log area ratio
.SH SYNOPSIS
.ft B
float
.br
lar_to_rc(lar)
.br
double lar;
.sp
.br
int 
.br
rc_to_lar(rc, lar)
.br
double rc;
float *lar;
.ft
.SH DESCRIPTION
.I lar_to_rc
converts the log area ratio
.I lar
to a reflection coefficient
.I rc
according to the formula:
.nf

	\fIrc\fR = [(\fIA\fR - 1)/(\fIA\fR + 1)]

.fi
where 
.I A
is the antilog (base 10) of 
.I lar.
.PP
.I rc_to_lar
converts the reflection coefficient 
.I rc
to a log area ratio 
.I lar
according to the formula
.nf

	\fIlar = \fRlog [(1 + \fIrc\fR)/(1 - \fIrc\fR)]

.fi
where the logarithm is to base 10.  If -1 < \fIrc\fR < +1, 
the value returned in 
.I lar
is computed according to the formula above and 
.I rc_to_lar 
returns the value 0.  
.PP
.IR rc " >= 1,"
the value returned in 
.I lar
is the system's maximum floating point value.  If 
.IR rc " <= -1,"
the value returned in 
.I lar
is the system's maximum negative floating point value.  
In both of these cases, 
.I rc_to_lar
returns the value 1.  
.SH EXAMPLE
float refco, logratio;
.br
refco = lar_to_rc(logratio);
.sp
float refco, logratio;
.br
if (rc_to_lar(refco, &logratio) != 0) 
.br
     fprintf(stderr, "WARNING - reflection coefficient out of range.\\n");
.SH DIAGNOSTICS
None, other than the function return value.  
.SH BUGS
None known.
.SH "SEE ALSO"
.nf
\fIlarcbk2rc\fP(1\-ESPS)
.fi
.SH AUTHOR
Manual page by John Shore