rfft.txt

DTW+VQ实现的语音识别 UIUC提供

function y=rfft(x,n,d)
%RFFT     Calculate the DFT of real data Y=(X,N,D)
% Data is truncated/padded to length N if specified.
%   N even:    (N+2)/2 points are returned with
%             the first and last being real
%   N odd:    (N+1)/2 points are returned with the
%             first being real
% In all cases fix(1+N/2) points are returned
% D is the dimension along which to do the DFT
%      Copyright (C) Mike Brookes 1998
%      Version: $Id: rfft.m,v 1.6 2008/05/22 20:00:28 dmb Exp $
%
%   VOICEBOX is a MATLAB toolbox for speech processing.
%   Home page: 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
%   http://www.gnu.org/copyleft/gpl.html or by writing to
%   Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

s=size(x);
if prod(s)==1
     y=x
 else
     if nargin <3
         d=find(s>1);
         d=d(1);
         if nargin<2
             n=s(d);
         end
     end
     if isempty(n) 
         n=s(d);
     end
     y=fft(x,n,d);
     y=reshape(y,prod(s(1:d-1)),n,prod(s(d+1:end))); 
     s(d)=1+fix(n/2);
     y(:,s(d)+1:end,:)=[];
     y=reshape(y,s);
 end