I am trying to use “asin()” and “acos()” to calculate the rotational angle of an arbitrary edge in the XZ plane. However, these functions seems to make Houdini crazy-unstable. The functions calculate the first or second time just fine. There after Houdini crashes and I must start over.

“User-Error” on the trig functions?

I'm thinking of abandoning the angle calculation and just using the “buildLookatRotation” function based on a faux object sitting on the perpendicular bisector.

Any other suggestions?

can you post a simple example file…that way we can get to the root of the problem

Thanks for the reply Michael -

Shucks - It seems by creating a “simple” example file I fixed my problem. (Or at least proven I did not have a problem. )
I must be creating the instability someplace else.

Regardless, I am posting my example hip file to demonstrate the numerical technique to calculate the rotation. The idea is to always make sure "point" is always pointing down the positive X-axis.

Thanks for your help