[Numpy-discussion] Slightly off-topic - accuracy of C exp function?
pav at iki.fi
Sun Apr 27 07:57:40 EDT 2014
27.04.2014 01:37, Matthew Brett kirjoitti:
> Take-home : exp implementation for mingw-w64 is exactly (floating
> point) correct 82% of the time, and one unit-at-the-last-place off for
> the rest . OSX is off by 1 ULP only 0.2% of the time.
> Is mingw-w64 accurate enough? Do we have any policy on this?
I think as mentioned, the C standards don't specify accuracy
requirements. Errors of a couple of ULP should be still acceptable.
Re: powell test --- if this turns out to be complicated to deal with,
just go ahead and disable the trace test.
Optimization routines contain statements of the form `if a > b: ...`
with floating point numbers, so that the execution path can be sensitive
to rounding error if you're unlucky, and the chances go up as the
iteration count increases.
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