ronjonp, I see what your saying. thanks.
Just going to need to make a check with a fuzz of 1/4 of a deg.
these points are generated from a user selecting points on a drawing so I guess some inacuracies should be expected.
(if (equal (result angle) (* pi 2.0) 0.00436332)
0.0
(result angle)
)
Thanks again for the input, nice to see a different angle on something.