Matrix norm   Hi Quietbritishjim thanks for the post on my talk page but it wasnt completely true what you wrote  The article states that the max norm is not submultiplicative hence not a matrix norm by the definition of matrix norms  You can show that multiplying the max norm by the dimension of the matrix makes it submultiplictive and hence an actual matrix norm see Horn and Johnson  Ill change it back if I dont hear back from you in a couple days  Cheers JDW