% MATLAB SIMULATION OF NSA FS-1016 CELP v3.2
% COPYRIGHT (C) 1995-99 ANDREAS SPANIAS AND TED PAINTER
%
% This Copyright applies only to this particular MATLAB implementation
% of the FS-1016 CELP coder.  The MATLAB software is intended only for educational
% purposes.  No other use is intended or authorized.  This is not a public
% domain program and distribution to individuals or networks is strictly
% prohibited.  Be aware that use of the standard in any form is goverened
% by rules of the US DoD.  Therefore patents and royalties may apply to
% authors, companies, or committees associated with this standard, FS-1016.  For
% questions regarding the MATLAB implementation please contact Andreas
% Spanias at (602) 965-1837.  For questions on rules,
% royalties, or patents associated with the standard, please contact the DoD.
%
% ALL DERIVATIVE WORKS MUST INCLUDE THIS COPYRIGHT NOTICE.
%
% ******************************************************************
% FIN
%
% PORTED TO MATLAB FROM CELP 3.2a C RELEASE
% 6-17-94
%
% ******************************************************************
%
% DESCRIPTION
%
% Distance measure conversion function, used by DIST.M
%
% DESIGN NOTES
%
% See references.
%
% REFERENCES
%
% 1. "Distance Measures for Speech Processing", A.H. Gray
%    and J.D. Markel, IEEE Trans. on ASSP, Vol. ASSP-24,
%    no. 5, Oct. 1976
%
% 2. "Quantization and Bit Allocation in Speech Processing",
%    A.H. Gray and J.D. Markel, IEEE Trans. on ASSP, Vol. ASSP-24
%    no. 6, Dec. 1976
%
% 3. "A Note on Quantization and Bit Allocation in Speech Processing",
%    A.H. Gray and J.D. Markel, IEEE Trans. on ASSP, Vol. ASSP-25
%    no. 3, June 1977
%
% VARIABLES
%
% INPUTS
%   z          -     Distance measure to be converted
%
% OUTPUTS
%   y          -     Converted distance measure
%
% CONSTANTS
%   DBFAC      -     dB conversion scale factor
%
% ******************************************************************

function y = fin( z )

% DEFINE LOCAL CONSTANTS
DBFAC = 4.342944819;

% DO THE CONVERSION
y = DBFAC * log( 1.0 + z + sqrt( z * ( 2.0 + z ) ) );