print "   result: ", $matrixM x $matrixX_assigned_value;

##</code><code>##

PDL: Dim mismatch in matmult of [2x2] x [2x1]: 2 != 1

##</code><code>##

print "should be: ", $matrixB_assigned_value;
print "   result: ", $matrixX_assigned_value x $matrixM;

##</code><code>##

should be:
[
 [
  [5 8]
 ]
 [
  [10 -5]
 ]
]
   result:
[
 [
  [5 4]
 ]
 [
  [ 4 -5]
 ]
]