[Numpy-discussion] bug with numpy.linalg.eig for complex output

Nils Wagner nwagner at iam.uni-stuttgart.de
Fri Aug 18 02:21:38 CDT 2006


Bill Baxter wrote:
> If you do this:
> >>>  numpy.linalg.eig(numpy.random.rand(3,3))
>
> You'll (almost always) get a wrong answer back from numpy.  Something
> like:
>
> (array([ 1.72167898, -0.07251007, -0.07251007]),
>  array([[ 0.47908847,  0.72095163,  0.72095163],
>        [ 0.56659142, -0.46403504, -0.46403504],
>        [ 0.67040914,  0.01361572,  0.01361572]]))
>
> The return value should be complex (unless rand() just happens to
> return something symmetric).
>
> It really needs to either throw an exception, or preferably for this
> function, just go ahead and return something complex, like the
> numpy.dft functions do.
> On the other hand it, would be nice to stick with plain doubles if the
> output isn't complex, but I'd rather get the right output all the time
> than get the minimal type that will handle the output.
>
> This is with beta 1.
>
> Incidentally, I tried logging into the Trac here:
> http://projects.scipy.org/scipy/scipy
> to file a bug, but it wouldn't let me in under the account I've been
> using for a while now.  Is the login system broken?  Were passwords
> reset or something?
>
>
> --bb
>
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AFAIK this problem is fixed.

http://projects.scipy.org/scipy/numpy/ticket/215

I have no problem wrt the Trac system.

Nils





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