[Numpy-discussion] lstsq illegal instruction

Angus McMorland amcmorl at gmail.com
Wed Nov 18 16:54:37 EST 2009

2009/11/18 Robert Kern <robert.kern at gmail.com>:
> On Wed, Nov 18, 2009 at 15:15, Angus McMorland <amcmorl at gmail.com> wrote:
>> Hi all,
>> Whenever I run numpy.linalg.lstsq with a xs parameter with both
>> dimensions larger than 128, I get an "Illegal instruction" and python
>> dies completely. It happens with both the Ubuntu jaunty standard numpy
>> 1.2.1, and a recent svn 1.4.0.dev7727, but it doesn't seem to happen
>> on any other machines. Anyone have any idea what might be causing
>> this? It's most annoying.
> This is almost always caused by using an ATLAS that is built for a
> different CPU than yours. Usually, the CPU that built the ATLAS
> binaries has SSE2 instructions while your CPU doesn't.

Many thanks for the pointer, Robert.

In case anyone else comes across the same problem, installing
libatlas3gf-sse2 made the problem go away; previously I only had the
python-scipy dependency libatlas3gf-base installed.

AJC McMorland
Post-doctoral research fellow
Neurobiology, University of Pittsburgh

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