www.pudn.com > voicebox2.zip > IRDCT.M

function x=irdct(y,n) 
%IRDCT    Inverse discrete cosine transform of real data X=(Y,N)  
% Data is truncated/padded to length N. 
% 
% This routine is equivalent to multiplying by the matrix 
% 
%    irdct(eye(n)) = cos((0.5:n)'*(0:n-1)*pi/n)*diag([sqrt(0.5) ones(1,n-1)])/n 
% 
% See also RCDT for further discussion 
 
%      Copyright (C) Mike Brookes 1998 
% 
%      Last modified Thu Sep 10 07:39:22 1998 
% 
%   VOICEBOX is a MATLAB toolbox for speech processing. Home page is at 
%   http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 
% 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
%   This program is free software; you can redistribute it and/or modify 
%   it under the terms of the GNU General Public License as published by 
%   the Free Software Foundation; either version 2 of the License, or 
%   (at your option) any later version. 
% 
%   This program is distributed in the hope that it will be useful, 
%   but WITHOUT ANY WARRANTY; without even the implied warranty of 
%   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the 
%   GNU General Public License for more details. 
% 
%   You can obtain a copy of the GNU General Public License from 
%   ftp://prep.ai.mit.edu/pub/gnu/COPYING-2.0 or by writing to 
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 
 
fl=size(y,1)==1; 
if fl y=y(:); end 
[m,k]=size(y); 
if nargin<2 n=m; 
elseif n>m y=[y; zeros(n-m,k)]; 
elseif n