Many people help Mike Meyer:
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 didn't follow this discussion, so I might have missed some essential
issues, I apologize then. But if THIS is the problem...
All these powerful universal libraries, with several hundreds of lines
of code are important and useful, but if the problem is to find whether
a list of pairs (x,y) is collinear or not, I presume that such program
as below could do. I am ashamed showing something like that...
*colin ((x,y):l) = all (\(c,d)->abs(px*d-py*c)