Sssasss wrote: > hi evrybody! > > I wan't to multiply two square matrixes, and i don't understand why it > doesn't work. > Could you explain me? > > def multmat(A,B): > "A*B" > if len(A)!=len(B): return "error"
Wrong validation here: you _can_ multiply two matrices with a different number of rows! And instead of returning "error" you should raise an exception. [...] I suggest using a linear algebra package, but if you insist in using lists of lists: >>> b = [[1, 2, 3, 4], ... [4, 5, 6, 7], ... [7, 8, 9, 10]] >>> >>> a = [[1, 2, 3], ... [4, 5, 6]] >>> >>> ab = [[sum(i*j for i, j in zip(row, col)) for col in zip(*b)] for row in a] >>> ab [[30, 36, 42, 48], [66, 81, 96, 111]] Straightforward from the definition of matrix multiplication. -- Roberto Bonvallet -- http://mail.python.org/mailman/listinfo/python-list
