[Gridflow-dev] geometry, cross products, matrix inversions...

Mathieu Bouchard matju at artengine.ca
Mon Nov 21 03:07:40 EST 2011

Le 2011-11-19 à 22:32:00, mescalinum at gmail.com a écrit :

> it involves a 3x3 times 3x1 inner product, but requires some 
> #pack/#unpack trickery. would you do it in some alternative way?

use [# cross], added 2 minutes ago. Should be much faster than any of my 3 
first solutions.

> also, what about computing the adjoint[1] of a matrix?
> [1] http://en.wikipedia.org/wiki/Adjugate_matrix

a fast way would use [# cross] preceded by some amount of preparation.
Using two 3x3 matrices, [# cross] will do 3 cross products.

[#store] allows to easily select rows from a matrix (but not columns). You 
just give it a column-matrix of indices (3 1 # ...).

Post your patch when you're done. :)

| Mathieu BOUCHARD ----- téléphone : +1.514.383.3801 ----- Montréal, QC

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