theorem Th13: :: MATRIXC1:14

for i, j being Nat
for M1, M2 being Matrix of COMPLEX st len M1 = len M2 & width M1 = width M2 & [i,j] in Indices M1 holds
(M1 - M2) * (i,j) = (M1 * (i,j)) - (M2 * (i,j))