matrix Multiplication

[Sssasss]

Fredrik Lundh wrote:
> "Sssasss" wrote:
>
> > I wan't to multiply two square matrixes, and i don't understand why it
> > doesn't work.
> >
> > def multmat(A,B):
> >    "A*B"
> >    if len(A)!=len(B): return "error"
> >    D=[]
> >    C=[]
> >    for i in range(len(A)): D.append(0)
> >    for i in range(len(A)): C.append(D)
>
> append doesn't copy data, so you're basically adding len(A) references to
> the same D list to C.  for more on this, see:
>
>     http://pyfaq.infogami.com/how-do-i-create-a-multidimensional-list
> 
> </F>

Ok!! Tank you very much, i understand now.

ciao