I have encountered some problems that have to do with the derivatives of matrices... I have NO experience with these and had little luck finding any theorems... I looked on wikipedia for some help and found a few definitions, but I am still unclear about how this is proven or attained... here is an example from wikipedia: d tr(AXB)/ dX = A^T B^T my question is... how are they getting that?!? I seem to be having a big mind block with this.. Any theorems about how to take derivatives of vectors or matrices would be great! any help would be appreciated!