What's wrong with this Simulated Annealing code ?

This is code for SA, to solve TSP. Can someone check it, where it go wrong ? I want: 500 particles to be used; 1000 iterations

function:

    function [c] = cost(x,y)
n=length(x);
c=0;
for i=1:n-1
c =c+ dist(x(i), x(i+1))
end

Program:

    n=20;
x=rand(1,n); y=rand(1,n);
x(end+1) = x(1);
y(end+1) = y(1);
figure(1);
hold off;
g=plot(x,y,'.r');
set(g,'MarkerSize',20);
c0=cost(x,y);
k=1;
nt=50; nr=200; 
for i=1:nt
T=1.0 -(i-1)/nt
for j=1:nr 
ic1 = randi([2,n]);
ic2 = randi([2,n]);
xs=x(ic1); ys=y(ic1);
x(ic1)=x(ic2); y(ic1)=y(ic2);
x(ic2)=xs; y(ic2)=ys;
p=rand(); 
c=cost(x,y);
if (c < c0 | p < exp(-(c-c0)/(k*T)))
c0=c;
else
xs=x(ic1); ys=y(ic1);
x(ic1)=x(ic2); y(ic1)=y(ic2);
x(ic2)=xs; y(ic2)=ys;
end
cp(j,i)=c0;
end
figure(2); 
plot(cp(:));
drawnow;
figure(1); hold off;
g=plot(x,y,'.r');
set(g,'MarkerSize',20); hold on;
plot(x,y,'b');
g=plot(x(1),y(1),'.g'); 
set(g,'MarkerSize',30);
drawnow;
end