# v_lpcar2rr

## PURPOSE

V_LPCAR2RR Convert autoregressive coefficients to autocorrelation coefficients RR=(AR,P)

## SYNOPSIS

function rr=v_lpcar2rr(ar,p)

## DESCRIPTION

    V_LPCAR2RR Convert autoregressive coefficients to autocorrelation coefficients RR=(AR,P)
     The routine calculated the autocorrelation coefficients of the signal
     that results from feeding unit-variance, zero-mean noise into the all-pole filter
     Input:   ar(:,n+1)  Autoregressive coefficients including 0'th coefficient
     Output:  rr(:,p+1)    Autocorrelation coefficients including 0'th order coefficient
     If p is not specified it is taken to be n

## CROSS-REFERENCE INFORMATION

This function calls:

- v_lpcar2rf V_LPCAR2RF Convert autoregressive coefficients to reflection coefficients AR=(RF)
- v_lpcrf2rr V_LPCRR2AR convert reflection coefs to autocorrelation coefs [RR,AR]=(RF,P)

This function is called by:

- v_distchar V_DISTCHAR calculates the cosh spectral distance between AR coefficients D=(AR1,AR2,MODE)
- v_distisar V_DISTISAR calculates the Itakura-Saito distance between AR coefficients D=(AR1,AR2,MODE)
- v_distitar V_DISTITAR calculates the Itakura distance between AR coefficients D=(AR1,AR2,MODE)
- v_meansqtf V_AVEPSPEC calculates the mean square transfer function for a filter D=(B,A)

## SOURCE CODE

    0001 function rr=v_lpcar2rr(ar,p)
    0002 %V_LPCAR2RR Convert autoregressive coefficients to autocorrelation coefficients RR=(AR,P)
    0003 % The routine calculated the autocorrelation coefficients of the signal
    0004 % that results from feeding unit-variance, zero-mean noise into the all-pole filter
    0005 % Input:   ar(:,n+1)  Autoregressive coefficients including 0'th coefficient
    0006 % Output:  rr(:,p+1)    Autocorrelation coefficients including 0'th order coefficient
    0007 % If p is not specified it is taken to be n
    0008
    0009
    0010 %      Copyright (C) Mike Brookes 1997
    0011 %      Version: $Id: v_lpcar2rr.m 10865 2018-09-21 17:22:45Z dmb $
    0012 %
    0013 %   VOICEBOX is a MATLAB toolbox for speech processing.
    0014 %   Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html
    0015 %
    0016 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0017 %   This program is free software; you can redistribute it and/or modify
    0018 %   it under the terms of the GNU Lesser General Public License as published by
    0019 %   the Free Software Foundation; either version 3 of the License, or
    0020 %   (at your option) any later version.
    0021 %
    0022 %   This program is distributed in the hope that it will be useful,
    0023 %   but WITHOUT ANY WARRANTY; without even the implied warranty of
    0024 %   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    0025 %   GNU Lesser General Public License for more details.
    0026 %
    0027 %   You can obtain a copy of the GNU Lesser General Public License from
    0028 %   https://www.gnu.org/licenses/ .
    0029 %
    0030 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
    0031
    0032 k=ar(:,1).^(-2);
    0033 if size(ar,2)==1
    0034    rr=k;
    0035 else
    0036    if nargin>1
    0037       rr=v_lpcrf2rr(v_lpcar2rf(ar),p).*k(:,ones(1,p+1));
    0038    else
    0039       rr=v_lpcrf2rr(v_lpcar2rf(ar)).*k(:,ones(1,size(ar,2)));
    0040    end
    0041 end