Dear R-listers Now I have a Matrix Equation to solve, A -- m by n matrix, where n>>m, known matrix; X -- n by m unknown matrix; B -- m by m known matrix. So given the equation A*X=B, how to solve X? I first tried to take X = inv((A'*A))*A'. But since A'*A is singular, this is no way to go. Please give me some point on this. Thanks Fred