clc;

N=10;
a=0;
b=10;
r=1;
X=a+r+(b-2*r)*rand(N,2);
t=0:0.01:2*pi;
for i=1:N
   x1=r*cos(t)+X(i,1);
   y1=r*sin(t)+X(i,2);
   fill(x1,y1,'g','FaceAlpha',0.5);
   hold on
end

X=reshape(X,2*N,1);
figure;
[x.opt y.opt]=fminsearch(@(x)fun(x1,a,b,r,X,N),X);
X=reshape(X,1*N,2);
for i=1:N
   x1=r*cos(t)+X(i,1);
   y1=r*sin(t)+X(i,2);
   fill(x1,y1,'r','FaceAlpha',0.5);
end