So, for both 1.5 and 1.6 (at least), it appears that the builtin sum does not add ndarrays the way "+" (and operator.add) do:
a = np.arange(10).reshape((2,5)) b = np.arange(10, 20).reshape((2,5)) sum(a,b) Out[5]: array([[15, 18, 21, 24, 27], [20, 23, 26, 29, 32]]) a + b Out[6]: array([[10, 12, 14, 16, 18], [20, 22, 24, 26, 28]]) Is this expected? I couldn't find a description of why this would occur in the mailing list or in the documentation. I can't figure out what sum does at all, actually, as it doesn't seem to be a case of strange broadcasting or any other tricks I tried. Yours, Chris -- ############################ Chris Mutel Ökologisches Systemdesign - Ecological Systems Design Institut f.Umweltingenieurwissenschaften - Institute for Environmental Engineering ETH Zürich - HIF C 44 - Schafmattstr. 6 8093 Zürich Telefon: +41 44 633 71 45 - Fax: +41 44 633 10 61 ############################ _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion