[Closed] Get Curve Controller Value at any time

Hello guys,
I feel a little embarassed because it seems something trivial but I can’t find the way to get it.
Let’s say I have a Rotation Controller (EulerXYZ) and I have two keys on frame 0 and 100 on rotationZ.
I want to know the value of the curve at frame 45, where there is no key… no matter what kind of tangents have the neighbouring keys. Of course, if they are Linear, problem is simple, but real life is not that simple… (Beziers, Steps, …) :).

Is there something I missed here ? How can I get value at a time where there is no key on the animation curve ?

Thanks for advance