I Need help to change random node arrangement to deterministic

for i=1:1:3

area(i)=0;

end

for i=1:1:n

%Getting random initial position of all the nodes

S(i).xd=rand(1,1)*xm;

XR(i)=S(i).xd;

S(i).yd=rand(1,1)*ym;

YR(i)=S(i).yd;

S(i).name=i;

X=S();

[C_id]= cluster_id(X,i);

S(i).id=C_id;