[Numpy-discussion] Core math library in numpy

Charles R Harris charlesr.harris@gmail....
Mon Feb 23 16:01:41 CST 2009


On Mon, Feb 23, 2009 at 2:02 PM, David Cournapeau <cournape@gmail.com>wrote:

> On Fri, Feb 20, 2009 at 5:26 PM, Pauli Virtanen <pav@iki.fi> wrote:
> > Fri, 20 Feb 2009 01:05:03 +0900, David Cournapeau wrote:
> > [clip]
> >>> I think they should be. Then we could easily use C99 complex math
> >>> functions on plaforms on which they are available (and so get the
> >>> "correct" corner-case semantics for free on these platforms).
> >>
> >> maybe we could change the names, then ? nc is not very clear IMHO (and
> >> since they were static up to now, we are free to change them I believe).
> >
> > I think it would make sense to change them to follow C99 function names,
> > with a npy_ prefix.
>
> The problem of complex functions is that they don't follow the C99
> conventions at all. IN particular, they accept pointers instead of
> values. I don't know whether the rational for using pointers is still
> valid (it is mentioned that how to pass structure is compiler


The usual rational is that it is more efficient to pass a pointer than to
push two floats on the stack. It is also an easier way to return values,
although recent versions of gcc do a good job of copying the return values
where they need to go. I would stick with the pointers, although we could
probably dispense with the structure and just use a pointer to the
underlying type with the assumption that the real & imaginary parts are
contiguous in memory. The ufuncs make that assumption in any case.

Chuck
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