m, a matrix, a map m : F <--- P between free modules of ranks f and p.

n, a matrix, a map n : G <--- Q between free modules of ranks g and q.

Outputs:

h, a matrix, a matrix with the shape h : F ** dual G <--- P ** dual Q, whose entry in the slot h_{g*i+j,q*k+l} is the result of differentiating n_{j,l}, by m_{i,k}