[Numpy-discussion] Slightly off-topic - accuracy of C exp function?

Pauli Virtanen 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 [1].  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.

Pauli Virtanen

More information about the NumPy-Discussion mailing list