Solution to overdetermined systems

Question

How to find solution to overdetermined systems in Macsyma, Scilab, Octave?

Answer 1

The backslash operator gives the least-squares solution in Scilab.

Answer 2

You don't say what type of system it is. If it is non-linear, you are in a very serious mess. In the linear case, You are trying to solve the system Ax = y, where A is not invertible. Even though it is not invertible, it admits a pseudo inverse, which you can stably compute using SVD.