[Numpy-discussion] Numpy.linalg.eig oddity

Salim, Fadhley (CA-CIB) fadhley.salim@ca-cib....
Wed Jun 23 13:25:17 CDT 2010


I've been investigating a truly bizarre bug related to the use of
numpy.linalg.eig.

I have two classes which both use numpy.linalg.eig. These classes are
used at very different times and are not connected in any way other than
the fact that they both share this particular dependancy. 

I have found that whichever class is called second will produce a
slightly different answer if numpy.linalg.eig is used sometime earlier.
I've eliminated all other variables besides the call to eig(). This
seems completely implausible, and yet I have the data.

As far as I am aware, eig() is wholly stateless and therefore using it
should not affect any subsequent calls to the function, right?

Numpy==1.2.1, Scipy==0.7.0

I've checked the bug-trac for this function and can find no references
to bugs which cause it to hold-state, even in the somewhat out of date
version of numpy. Can somebody let me know if there's something that I'm
missing.
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