[Numpy-discussion] inplace dot products
Olivier Grisel
olivier.grisel@ensta....
Wed Feb 18 03:06:26 CST 2009
Hi numpist people,
I discovered the ufunc and there ability to compute the results on
preallocated arrays:
>>> a = arange(10, dtype=float32)
>>> b = arange(10, dtype=float32) + 1
>>> c = add(a, b, a)
>>> c is a
True
>>> a
array([ 1., 3., 5., 7., 9., 11., 13., 15., 17.,
19.], dtype=float32)
My questions is : is there a way to have an equivalent for the dot
product operation:
I want atlas to build my dot products without allocating a temporary
array and reuse
a preallocated array of results. Suppose I have:
>>> results = array((10, 3), dtype=float32)
>>> W = arange(6, dtype=float32).reshape((2, 3))
>>> x = arange(20, dtype=float32).reshape((10, 2))
What I want is the equivalent of the following without the
intermediate call to malloc:
>>> results[:] = dot(x, W)
Any idea? I tried to introspect the various docstring of numpy core
modules but I
could not get any lead.
--
Olivier
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