[Numpy-discussion] Iterative Matrix Multiplication

josef.pktd@gmai... josef.pktd@gmai...
Sun Feb 28 19:45:29 CST 2010


On Sun, Feb 28, 2010 at 7:53 PM, Ian Mallett <geometrian@gmail.com> wrote:
> Hi,
>
> I have a list of vec3 lists (e.g. [[1,2,3],[4,5,6],[7,8,9],...]). To every
> single one of the vec3 sublists, I am currently applying transformations.  I
> need to optimize this with numpy.
>
> To get proper results, as far as I can tell, the vec3 lists must be
> expressed as vec4s: [[1,2,3],[4,5,6],[7,8,9],...] ->
> [[1,2,3,1],[4,5,6,1],[7,8,9,1],...].   Each of these needs to be multiplied
> by either a translation matrix, or a rotation and translation matrix.
>
> I don't really know how to approach the problem . . .

I'm not sure what exactly you need but it sounds similar to
"Row-wise dot product" in numpy-discussion Sept 2009

there are several threads on rotation matrix, which might be useful
depending on the structure of your arrays

Josef


>
> Thanks,
> Ian
>
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