I have a large (40,000 x 128) Numeric array, X, with typecode Float. In some cases the number of rows may be approx 10x greater. I want to create an array Y with the same dimensions as X, where each element of Y is the corresponding element of X with the mean of the row on which it occurs subtracted away. Ie, Y = X - transpose(resize(mean(X,1), (X.shape[1],X.shape[0]))) I am wondering if this is the most efficient way (speed and memory). Thanks for any suggestions, John Hunter