Always false float comparisons

[jmh530 via Digitalmars-d]

On Tuesday, 17 May 2016 at 07:47:58 UTC, Ethan Watson wrote:
>
> Unless you're doing game/graphics work ;-) 4x3 or 4x4 matrices 
> are commonly used to represent transforms in 3D space in every 
> 3D polygon-based rendering pipeline I know of. It's even a 
> requirement for fixed-function OpenGL 1.x.
>
> Video games - also known around here as "The Exception To The 
> Rule".
>
> (Side note: My own preference is to represent transforms as a 
> quaternion and vector. Inverting such a transform is a simple 
> matter of negating a few components. Generating a matrix from 
> such a transform for rendering purposes is trivial compared to 
> matrix inversion.)

I don't know much about computer graphics, but if you're solving 
equations, then you can use the techniques mentioned above.

Nevertheless, I'm not really sure what would be the fastest 
approach to inverting small matrices. I would definitely try the 
LU or Cholesky approaches. It might be that for a small matrix a 
Gaussian reduction approach would be fast. There are some 
analytic tricks you could use if you have some information about 
them, like when you can represent them as blocks. If some of the 
blocks are zero or identity matrices, then it simplifies the 
calculations too.