Maxima Function
copymatrix (M)
Returns a copy of the matrix M. This is the only way to make a copy aside from copying M element by element.
Note that an assignment of one matrix to another, as in m2: m1,
does not copy m1.
An assignment m2 [i,j]: x or setelmx (x, i, j, m2 also modifies m1 [i,j].
Creating a copy with copymatrix and then using assignment creates a separate, modified copy.