On Nov 14, 1:51 pm, William Stein <wst...@gmail.com> wrote:
> Hi,
>
> This thread is about sum.
>
> 1. Dima said:
>
> > I don't think sum() method is needed. It's certainly a code bloat.
>
> This is a very, very misinformed comment. I want to address it,
> especially the statement "It's certainly a code bloat."
Sorry if I sounded too categorical on this.
I suppose I meant two things:
1) self.sum() on vectors is not too useful.
A fast scalar product would be much more useful than .sum().
2) wanting a fast sum (or a scalar product), that works faster than
Python's function sum(), yet does not require a handwritten code in
every vector*.pyx, one seems to be hitting the limitation of Cython,
which lacks generics.
The code from TimeSeries:
cpdef double sum(self):
...
cdef double s = 0
cdef Py_ssize_t i
for i from 0 <= i < self._length:
s += self._values[i]
return s
is totally generic, except the type declaration. If Cython had
generics (aka templates) one would have written
cpdef T sum(self):
...
cdef T s = 0
cdef Py_ssize_t i
for i from 0 <= i < self._length:
s += self._values[i]
return s
in the parent class of a vector class over T, rather than in the
vector classes, for T=double, etc etc themselves.
(Perhaps something like this can still be accomplished within Sage,
but I don't see how.)
Dima
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