contract'(Matrix,Matrix) -- contract a matrix by a matrix, the dual notion

• Function: contract'

• Usage:

  h = contract'(m,n)

• Inputs:
  • 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 contracting m_i,k, by n_j,l.