[Numpy-discussion] Vote: complex64 vs complex128

Sebastian Haase haase at msg.ucsf.edu
Tue Apr 4 09:33:07 CDT 2006


On Tuesday 04 April 2006 08:09, Charles R Harris wrote:
> I can't get worked up over this one way or the other: complex128 make sense
> if I count bits, complex64 makes sense if I note precision; I just have to
> remember the numpy convention. One could argue that complex64 is the more
> conventional choice and so has the virtue of least surprise, but I don't
> think it is terribly difficult to become accustomed to using complex128 in
> its place. I suppose this is one of those programmer's vs user's point of
> view thingees. For the guy writing general low level numpy code what
> matters is the length of the type, how many bytes have to be moved and so
> on, and from the other point of view what counts is the precision of the
> arithmetic.

I kind of like your comparison of  programmer vs user ;-)
And so I was "hoping" that numpy (and scipy !!) is intended for the users - 
like supposedly IDL and Matlab are...

No one likes my "backwards compatibility" argument !?

Thanks
- Sebastian Haase

PS: I understand that voting is only for a last resort - some people, always 
use na.Complex and na.Float and don't care - BUT I use single precision all 
the time because my image data is already getting to large.  So I have to  
look at this every day, and as Travis pointed out, now is about the last 
chance to possibly change  complex128 to complex64 ...

>
> Chuck
>
> On 4/4/06, Colin J. Williams <cjw at sympatico.ca> wrote:
> > Sebastian Haase wrote:
> > > Hi,
> > > Could we start another poll on this !?
> > >
> > > I think I would vote
> > > +1  for complex32 & complex64  mostly just because of "that's what I'm
> > > used to"
> >
> > +1 Most people look to the number to give a clue as to the precision of
> > the value.
> >
> > Colin W.
> >
> > > But I'm curious to hear what others "know to be in use" - e.g. Matlab
> > > or IDL !
> > >
> > > - Thanks
> > > Sebastian Haase
> > >
> > > Travis Oliphant wrote:
> > >> Sebastian Haase wrote:
> > >>> Tim Hochberg wrote:
> > >>> <snip>
> > >>>
> > >>>> This would work fine if repr were instead:
> > >>>>
> > >>>>    dtype([('x', float64), ('z', complex128)])
> > >>>>
> > >>>> Anyway, this all seems reasonable to me at first glance. That said,
> > >>>> I don't plan to work on this, I've got other fish to fry at the
> > >>>> moment.
> > >>>
> > >>> A new point: Please remind me (and probably others): when did it get
> > >>> decided to introduce 'complex128' to mean numarray's complex64
> > >>> and the 'complex64' to mean numarray's complex32 ?
> > >>
> > >> It was last February (i.e. 2005) when I first started posting
> > >> regarding the new NumPy.   I claimed it was more consistent to use
> > >> actual bit-widths.   A few people, including Perry, indicated they
> > >> weren't opposed to the change and so I went ahead with it.
> > >>
> > >> You can read relevant posts by searching on
> > >> numpy-discussion at lists.sourceforge.net
> > >>
> > >> Discussions are always welcome.  I suppose it's not too late to
> > >> change something like this --- but it's getting there...
> > >>
> > >> -Travis




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