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

[mescalinum at gmail.com]

Il 21/11/2011 09:07, Mathieu Bouchard ha scritto:
> 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. :)

could be an example of using [# cross] (other than [# cross] used for 
doing cross products!)



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