gusucode.com > 语音信号处理工具箱 - Voicebox源码程序 > Voicebox\permutes.m
function [p,s]=permutes(n) %PERMUTES All N! permutations of 1:N + signatures [P,S]=(N) % The output P is a matrix of size (N!,N) where each row % contains a permutation of the numbers 1:N. The rows are in % lexically sorted order. % % To permute the elements of an arbitrary vector V use % V(PERMUTES(LENGTH(V))). % PERMUTES(N) is the same as SORTROWS(PERMS(1:N)) but much faster. % Thanks to Peter J Acklam for several improvements. % Copyright (c) 1998 Mike Brookes, mike.brookes@ic.ac.uk % % Last modified Thu May 21 18:18:10 1998 % % VOICEBOX 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 % 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. %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% p=1; m=1; if n>1 for a=2:n q=zeros(a*m,a); r=2:a+1; ix=1:m; for b=1:a q(ix,1)=b; q(ix,2:a)=r(p); r(b)=b; ix=ix+m; end m=m*a; p=q; end end if nargout>1 s=1-2*rem(fix((1:m)'/2),2); end