I am seeing a problem on Solaris since I upgraded to svn HEAD. np.isinf does not handle np.inf. See ipython session below. I am not seeing this problem w/ HEAD on an ubuntu linux box I tested on In [1]: import numpy as np In [2]: np.__version__ Out[2]: '2.0.0.dev8480' In [3]: x = np.inf np.inf np.info np.infty In [3]: x = np.inf In [4]: np.isinf(x) Warning: invalid value encountered in isinf Out[4]: True In [5]: np.seter np.seterr np.seterrcall np.seterrobj In [5]: np.seterr(all='raise') Out[5]: {'over': 'print', 'divide': 'print', 'invalid': 'print', 'under': 'ignore'} In [6]: np.isinf(x) --------------------------------------------------------------------------- FloatingPointError Traceback (most recent call last) /home/titan/johnh/<ipython console> FloatingPointError: invalid value encountered in isinf In [7]: !uname -a SunOS udesktop191 5.10 Generic_139556-08 i86pc i386 i86pc In [43]: !gcc --version gcc (GCC) 3.4.3 (csl-sol210-3_4-branch+sol_rpath) Copyright (C) 2004 Free Software Foundation, Inc. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. Posted on tracker: http://projects.scipy.org/numpy/ticket/1547