Hi
I'm a beginner of Houdini as well as poor math ability,(but a true heart for FX:lol

I got a wired scenario of sine function

should be 0.5, but I got a negative result -0.988032

Could someone tell me why please~~

Regards,
jessica

Sine node works with radians. So -0.988 should be fine. Depending on what you are after you can use the “degrees to radians” node before your sine node.

You can insert a deg_to_rad VOP inbetween the const1 Constant VOP and the sine2 Sine VOP to convert your degrees to radians as mentioned above.

Tip to remember is that anything to do with VOPs/VEX is always radians, while older school SOPs that use Houdini expressions are in degrees.

When you build tools in VOPs or VEX wranglers, always promote your rotation parameters using angles in degrees and not radians. No artist I have ever met worth their salt thinks of angles in radians.

That is why you use the Deg to Rad VOP.