On 1 November 2015 at 10:04, gers antifx <schweiger.ger...@gmail.com> wrote: > > I have to write a LU-decomposition. My Code worked so far but (I want to > become better:) ) I want to ask you, if I could write this LU-decomposition > in a better way? > > def LU(x): > L = np.eye((x.shape[0])) > n = x.shape[0] > for ii in range(n-1): > for ll in range(1+ii,n): > factor = float(x[ll,ii])/x[ii,ii] > L[ll,ii] = factor > for kk in range(0+ii,n): > x[ll,kk] = x[ll,kk] - faktor*x[ii,kk] > LU = np.dot(L,x)
You're using ii and ll, kk etc. This is common practise in Matlab code because Matlab uses i as sqrt(-1) but this is spelled 1j in Python so we don't have that problem. In this sort of context it would be more natural to use simply i, j, k in Python. Another is that you're not checking for divide by zero in float(x[ll,ii])/x[ii,ii]. Are you sure that it will not be zero? What happens if e.g. x[0, 0] is zero? This is where you'll need to use pivoting which complicates the algorithm a bit. -- Oscar -- https://mail.python.org/mailman/listinfo/python-list
