[Numpy-discussion] Does float16 exist?

Charles R Harris charlesr.harris@gmail....
Tue Jan 8 21:36:34 CST 2008


On Jan 8, 2008 6:49 PM, Eric Firing <efiring@hawaii.edu> wrote:

> Bill Baxter wrote:
> > On Jan 9, 2008 9:18 AM, Charles R Harris <charlesr.harris@gmail.com>
> wrote:
> >> On Jan 8, 2008 5:01 PM, Bill Baxter <wbaxter@gmail.com> wrote:
> >>> On Jan 9, 2008 8:03 AM, Charles R Harris <charlesr.harris@gmail.com>
> >> wrote:
> >>>> On Jan 8, 2008 1:58 PM, Bill Baxter < wbaxter@gmail.com> wrote:
> >>>>> If you're really going to try to do it, Charles, there's an
> >>>>> implementation of float16 in the OpenEXR toolkit.
> >>>>> http://www.openexr.com/
> >>>>>
> >>>>> Or more precisely it's in the files in the Half/ directory of this:
> >>>>>
> >>
> http://download.savannah.nongnu.org/releases/openexr/ilmbase-1.0.1.tar.gz
> >>>>> I don't know if it's IEEE conformant or not (especially w.r.t. NaN's
> >>>>> and such) but it should be a good start.  The code seems to be well
> >>>>> documented.
> >>>> The license looks good, essentially BSD. The code is all C++, which
> is
> >> the
> >>>> obvious way to go for this sort of thing, and I would like to stick
> with
> >> it,
> >>>> but that could lead to build/compatibility problems. I think NumPy
> >> itself
> >>>> should really be in C++.  Maybe scons can help with the build.
> >>> Yeh, I was just thinking you'd rip out and C-ify the main algorithms
> >>> rather than trying to wrap it as-is.
> >> I'd rather not C-ify the thing, I'd rather C++-ify parts of NumPy. I
> note
> >> that MatPlotLab uses C++, so some of the problems must have been
> solved.
>
> A big chunk of C++ in matplotlib has just been replaced, largely because
> it was so hard to understand and extend for everyone but its author.
> There is still C++ code as well as C code in mpl.  Personally, I prefer
> the C.
>
> >
> > If you think that's easier then go for it.
>
> The opinion that C++ would improve numpy is not universal, and has been
> discussed.
>
> http://article.gmane.org/gmane.comp.python.numeric.general/13244
>

Ah, the trick to interfacing C to C++ is to derive the C++ classes from the
numpy structures and keep the function pointers. Then all the offsets would
work. I would think the main advantage of C++ would be in arithmetic
operator overloading and using template classes while carefully restricting
such things to numbers. Mostly, I would use C++ inline class methods as
shorthand that would compile to what the C approach would do. I suppose we
could write a python preprocessor that would do essentially the same thing;
C++ started that way.

Chuck
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