[Haskell-cafe] Coplanarity or Colinearity [Was: low-cost matrix rank?]
carter.schonwald at gmail.com
Sat Apr 25 15:00:01 UTC 2015
Shewchuk has a good number of writings in this topic including this
random one i found. page 9 appears to be the releavant one?
On Sat, Apr 25, 2015 at 10:20 AM, Ertugrul Söylemez <ertesx at gmx.de> wrote:
> >> 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?
> > I have written an experimental [implementation] of a Gauss-Jordan solver
> > and matrix inverter. You might find some use for it. It does work and
> > is reasonably fast, though not as fast as hmatrix. One advantage is
> > that you can feed the points incrementally, and it will tell you
> > immediately when there is no solution. It will also quickly reject
> > redundant points, even in the presence of rounding errors.
> I should note: The `solve` function isn't yet written, but it also
> doesn't do much. Once you have fed enough relations, the matrix will
> already have been reduced to the identity, so you can simply extract the
> solutions from the relations.
> Haskell-Cafe mailing list
> Haskell-Cafe at haskell.org
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the Haskell-Cafe