What's the mathematical principle of PlaneThroughPt?

Hi, all. Just as the title said, I hope to find out the mathematical principle PlaneThroughPt based on, so that I can tell if the plane it created is accurate enough for my research. What’s more, as a beginner, I really want some information about the basic principle of Rhino and it’s commands, where can I find something like that? Thanks!

Hello - I believe it is a least-squares fit, but I’m not certain, I’ll see what I can find out.

-Pascal

If I remember correctly, it’s using a “least squares” method to fit to the selected points: