[SciPy-User] understanding machine precision
Tue Dec 14 12:47:04 CST 2010
On Tue, Dec 14, 2010 at 12:42, Keith Goodman <firstname.lastname@example.org> wrote:
> On Tue, Dec 14, 2010 at 9:42 AM, <email@example.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)
>> x2 = scipy.linalg.lstsq(a0,b0)
>> print np.max(np.abs(x-x2))
> 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.
On OS X with numpy linked against the builtin Accelerate.framework
(which is based off of ATLAS), I get the same result every time.
"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
-- Umberto Eco
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