[Haskell-cafe] Coplanarity or Colinearity [Was: low-cost matrix rank?]

[Carter Schonwald]

Yes, solving it directly is probably a better tact.  I believe There's
quite a bit of research literature on this out there in the computational
geometry literature.

Have you looked at the CGal c++ lib to check if they have any specialized
code for low dimensional geoemtry? CGal or something like it is very likely
to have what you want.

Perhaps more importantly: what are your precision needs?  Cause some of
these questions have very real precision trade offs depending on your goals



On Saturday, April 25, 2015, Mike Meyer <mwm at mired.org> wrote:

> Well, none of the suggested solutions for computing the rank of a matrix
> really suited my needs, as dragging in something like BLAS introduce more
> cost than just integrating the bed-and-breakfast library into my own
> library. So let me try a different track.
>
> My real problem is that I've got a list of points in R3  and want to
> decide if they determine a plane, meaning they are coplanar but not
> colinear. Similarly, given a list of points in R2, I want to verify that
> they aren't colinear. Both of these can be done by converting the list of
> points to a matrix and finding the rank of the matrix, but I only use the
> rank function in the definitions of colinear and coplanar.
>
> Maybe there's an easier way to tackle the underlying problems. Anyone got
> a suggestion for such?
>
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