[Numpy-discussion] Taking a large number of dot products at once

Daniel Hyams dhyams@gmail....
Fri Mar 4 00:19:45 CST 2011


This is probably so easy, I'm embarrassed to ask it...but I've been casting
around trying things to no avail for the last hour and a half, so here
goes...

I have a lot of dot products to take.  The length-3 vectors that I want to
dot are stacked in a 2D array like this:

U = [u1 u2 u3....]

and

V = [v1 v2 v3....]

So both of these arrays, are, say, 3x100 each.  I just want to take the dot
product of each of the corresponding vectors, so that the result is

[u1.v1 u2.v2  u3.v3 ....]

which would be a 1x100 array in this case.

Which function do I need to use?  I thought tensordot() was the one, but I
couldn't make it work....pure user error I'm sure.
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