On Fri, May 30, 2014 at 9:38 PM, Josh English
> I am trying to whip up a quick matrix class that can handle multiplication.
> Should be no problem, except when it fails.
> def zero_matrix(rows, cols):
> row =  * cols
> data = 
> for r in range(rows):
Each row of the matrix that you create here is the *same* list, not
different lists that happen to be equal. So when you mutate one row,
you mutate all of them. See: