ali - your above code would never set a non-integer number as any element in the degree array since all you ever do is just increment any element by one. So I think that you have not provided the code that generates the error that you are observing.
One problem that I do see with your code is the use of degree. Why is it an nxn matrix where you consider each pair? Because that would mean that you would only ever have ones or zeros in this matrix. If you want to find the degree (number of neighbours) for each node, then if you have n nodes, your degree array would be nx1. And so your code would be as follows
if isfield(handles,'net')
n = numel(handles.net(1,:);
degrees = zeros(n,1);
for u=1:n
X1 = handles.net(2,u);
Y1 = handles.net(3,u);
for v=1:n
X2 = handles.net(2,v);
Y2 = handles.net(3,v);
xSide = abs(X2-X1);
ySide = abs(Y2-Y1);
d = sqrt(xSide^2+ySide^2);% distance euclidienne
DD(u,v)=d; %matrice de distance entre noeuds
%RESORTIR LES NOEUD REDONDANTS
if (DD(u,v)< 2*(handles.r))&&(u~=v)
degree(u)=degree(u)+1;
end;
end
end
end
