matthiasm@8: function M = setdiag(M, v)
matthiasm@8: % SETDIAG Set the diagonal of a matrix to a specified scalar/vector.
matthiasm@8: % M = set_diag(M, v)
matthiasm@8: 
matthiasm@8: n = length(M);
matthiasm@8: if length(v)==1
matthiasm@8:   v = repmat(v, 1, n);
matthiasm@8: end
matthiasm@8: 
matthiasm@8: % e.g., for 3x3 matrix,  elements are numbered
matthiasm@8: % 1 4 7 
matthiasm@8: % 2 5 8 
matthiasm@8: % 3 6 9
matthiasm@8: % so diagnoal = [1 5 9]
matthiasm@8: 
matthiasm@8: 
matthiasm@8: J = 1:n+1:n^2;
matthiasm@8: M(J) = v;
matthiasm@8: 
matthiasm@8: %M = triu(M,1) + tril(M,-1) + diag(v);
matthiasm@8: