rfft.m

语音处理平台 可以分析语音能量 第一振峰频率等数据

function y=rfft(x,n,d)
%RFFT     FFT of real data Y=(X,N)
% 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



%      Copyright (C) Mike Brookes 1998
%
%      Last modified Wed Jun  2 09:14:51 2004
%
%   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.
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

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