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

Charles R Harris charlesr.harris@gmail....
Mon Sep 29 23:14:33 CDT 2008


On Mon, Sep 29, 2008 at 9:54 PM, David Cournapeau <
david@ar.media.kyoto-u.ac.jp> wrote:

> Charles R Harris wrote:
> >
> >
> > On Mon, Sep 29, 2008 at 9:02 PM, David Cournapeau
> > <david@ar.media.kyoto-u.ac.jp <mailto:david@ar.media.kyoto-u.ac.jp>>
> > wrote:
> >
> >     Charles R Harris wrote:
> >     >
> >     > So the proposition is, sign, max, min return nan when any of the
> >     > arguments is nan.
> >
> >     Note that internally, signbit (the C function) returns an integer.
> >
> >
> > That is the signature of the ufunc. It could be changed...
>
> Nope, I am talking about the C99 signbit macro. man signbit tells me:
>
> NAME
>       signbit - test sign of a real floating point number
>
> SYNOPSIS
>       #include <math.h>
>
>       int signbit(x);
>
>       Compile with -std=c99; link with -lm.
>

Yes, that too. But I was thinking of the ufunc returning nan when needed.
However, I think -1 is the way to go for that to get minimal breakage.

Chuck
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