[SciPy-User] understanding machine precision

Keith Goodman kwgoodman@gmail....
Tue Dec 14 12:42:23 CST 2010


On Tue, Dec 14, 2010 at 9:42 AM,  <josef.pktd@gmail.com> wrote:
> I thought that we get deterministic results, with identical machine
> precision errors, but I get (with some random a0, b0)
>
>>>> for i in range(5):
>        x = scipy.linalg.lstsq(a0,b0)[0]
>        x2 = scipy.linalg.lstsq(a0,b0)[0]
>        print np.max(np.abs(x-x2))
>
>
> 9.99200722163e-016
> 9.99200722163e-016
> 0.0
> 0.0
> 9.99200722163e-016

I've started a couple of threads in the past on repeatability. Most of
the discussion ends up being about ATLAS. I suggest repeating the test
without ATLAS.


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