www.gusucode.com > 语音信号处理工具箱 - Voicebox源码程序 > Voicebox\rsfft.m
function x=srfft(y,n) %SRFFT fft of a real symmetric spectrum X=(Y,N) % The invere fft is the same function but divided by N % Y contains FIX(1+N/2) complex samples from the spectrum: if argument N % is specified then Y will be truncated or padded accordingly % IMPORTANT: If N is odd, it MUST be specified explicitly. % Copyright (C) Mike Brookes 1998 % % Last modified Wed Jan 30 09:44:15 2002 % % 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. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% if ~isreal(y) error('SRFFT: Input must be real'); end fl=size(y,1)==1; if fl y=y(:); end [m,k]=size(y); if nargin<2 n=2*m-2; else mm=1+fix(n/2); if mm>m y=[y; zeros(mm-m,k)]; elseif mm<m y(mm+1:m,:)=[]; end m=mm; end x=real(fft([y;y(n-m+1:-1:2,:)])); x(m+1:end,:)=[]; if fl x=x.'; end