On Tue, Apr 30, 2013 at 8:08 PM, Yaroslav Halchenko <lists@onerussian.com>wrote:
could anyone on 32bit system with fresh numpy (1.7.1) test following:
wget -nc http://www.onerussian.com/tmp/data.npy ; python -c 'import numpy as np; data1 = np.load("/tmp/data.npy"); print np.sum(data1[1,:,0,1]) - np.sum(data1, axis=1)[1,0,1]'
0.0
because unfortunately it seems on fresh ubuntu raring (in 32bit build only, seems ok in 64 bit... also never ran into it on older numpy releases):
python -c 'import numpy as np; data1 = np.load("/tmp/data.npy"); print np.sum(data1[1,:,0,1]) - np.sum(data1, axis=1)[1,0,1]' -1.11022302463e-16
Perhaps on the 32-bit system one call is using the 80-bit extended precision register for the summation and the other one is not? -Brad