function [c1,c2]=er(p1,p2,bounds,ops)% Er crossover takes two parents P1,P2 and performs edge recombination% crossover on permutation strings.  %% function [c1,c2] = er(p1,p2,bounds,Ops)% p1      - the first parent ( [solution string function value] )% p2      - the second parent ( [solution string function value] )% bounds  - the bounds matrix for the solution space% Ops     - Options matrix for simple crossover [gen #SimpXovers].% Binary and Real-Valued Simulation Evolution for Matlab % Copyright (C) 1996 C.R. Houck, J.A. Joines, M.G. Kay %% C.R. Houck, J.Joines, and M.Kay. A genetic algorithm for function% optimization: A Matlab implementation. ACM Transactions on Mathmatical% Software, Submitted 1996.%% 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 1, 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. A copy of the GNU % General Public License can be obtained from the % Free Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.sz=size(p1,2)-1;right=[2:sz 1];left =[sz 1:(sz-1)];p1i(p1)=1:sz; %Generate indexp2i(p2)=1:sz; %Generate indexadj=sort([-1:-1:-sz;p1(right(p1i));p1(left(p1i));p2(right(p2i));p2(left(p2i))])';repeats=find(diff(adj(:,2:5)')'==0);adj(repeats+sz)=zeros(size(repeats));curr_site = round(rand*sz + 0.5); %Pick random start sitefor site=1:(sz-1)  c1(site)=curr_site;  inAdj=find(adj(:,2:5)==curr_site); %Find this site in adjacency table  adj(inAdj+sz)=zeros(size(inAdj)); %Take this out of the adjacency table  %Find the element with fewest remaining links  lz=colperm(adj');  lzi(lz)=1:size(lz,2); %create index  adj_cities=adj(curr_site,1+(find(adj(curr_site,2:5))));  [v i]=min(lzi(adj_cities));  curr_site=adj_cities(i);endc1(sz)=curr_site;c2=p1;