[Numpy-discussion] What is the sign of nan?

Charles R Harris charlesr.harris@gmail....
Tue Sep 30 01:34:01 CDT 2008


On Tue, Sep 30, 2008 at 12:24 AM, Robert Kern <robert.kern@gmail.com> wrote:

> On Tue, Sep 30, 2008 at 00:46, Nathan Bell <wnbell@gmail.com> wrote:
> > On Tue, Sep 30, 2008 at 1:20 AM, Robert Kern <robert.kern@gmail.com>
> wrote:
> >>
> >> F.9.9.2 The fmax functions
> >> 1 If just one argument is a NaN, the fmax functions return the other
> >> argument (if both arguments are NaNs, the functions return a NaN).
> >> 2 The body of the fmax function might be
> >> {return (isgreaterequal(x, y) ||
> >>  isnan(y)) ? x : y; }
> >>
> >> If we want to follow C99 semantics rather than our own
> >> NaN-always-propagates semantics, then we should do this instead.
> >>
> >
> > +1 for NaN-always-propagates since we have explicit variants for the
> > alternative semantics.
> >
> > Users are more likely to remember that "NaNs always propagate" than
> > "as stated in the C99 standard...".
>
> OTOH, Python 2.6 and up will be following to the C99 standard as
> closely as possible. I would prefer to keep up with them. It's true
> that "as stated in the C99 standard" is more difficult to remember,
> but "NaNs always propagate" is probably not going to be consistent
> with everything we actually implement, no matter how hard we try.
>

I wonder how much of the Python stuff we can steal^W borrow. I assume the
Python license is compatible with numpy?

Chuck
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