[Numpy-discussion] output arguments

Thomas Breuel tmbdev@gmail....
Wed Jul 25 17:47:21 CDT 2007


> > For example, it would be nice if "outer"
> > supported:
> >
> > outer(b,c,output=a)
> > outer(b,c,increment=a)
> > outer(b,c,increment=a,scale=eps)
> >
> > or maybe one could specify an accumulation ufunc, with addition,
> > multiplication, min, and max being fast, and with an optional scale
> > parameter.
>
> What would the increment and scale parameters do? Why should they be part
> of the
> outer() interface? Have you looked at the .outer() method on the add,
> multiply,
> minimum, and maximum ufuncs?


output=a would put the output of the operation into a
increment=a would increment the values in a by the result of the operation
increment=a,scale=eps would increment the values in a by the result of
multiplying the result by eps.

I think a good goal for a numerical scripting language should be to allow
people to express common numerical algorithms without extraneous array
allocations for intermediate results; with a few dozen such primitives, a
lot of native code can be avoided in my experience.

> Another approach might be to provide, in addition to the convenient
> > high-level NumPy operations, direct bindings for BLAS and/or similar
> > libraries, with Fortran-like procedural interfaces, but I can't find any
> > such libraries in NumPy or SciPy.  Am I missing something?
>
> scipy.linalg.flapack, etc.


Thanks; I'll have to take a look. I don't remember whether LAPACK contains
these low-level ops itself.

Cheers,
Thomas.
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