Profile question

I've played a little with Excel, on a theo profile Y=2*SIN(X).
If you realize this profile, you can imagine different defects of size, orientation and vibrations, so the measured hits are following a function like Y1=A*(sin(X)+ random value) + B*X + C.
The form only must fit this function, but the form + location just look at the measured hits.
This gives those results :

I entered A=1.96, B=0.03, C=0.05 + a random on Y value, the LS calculation givesA=1.961, B=0.026 and C=0.058.
The min max value for form only give ±0.080, but the differnece between hits and theo profile is +0.254, + 0.001.
The first result is the difference along Y between the red curve and hits, the second is the difference between green curve (theo) and hits.
The result should be different if I used distance along the normal vector (using LS + vector on PC-DMIS) instead of distance along Y (LS only).

Hope it can help, not sure of it, but it was a pleasure to play with a sinus !!!!!!!!!!

If Hexagon ever needs a math wiz... choose this guy.

If Hexagon ever needs a math wiz... choose this guy.