Spline in a confined region

Hi everybody,

I'm trying to do a closed cubic spline passing from 5 different points, that are inside a circle. Anyway, I want that this spline remains inside the first and second quadrant (if you imagine a cartesian plane, with x and y axis passing from the origin of the circle).

How can I do this?

Thank you very much!

[Image Analyst]

Attach your knot (training) points. In the meantime, see my attached spline demos.

[Gianmarco Azzolin]

Thank you!

[Image Analyst]

OK, but you forgot the attachment.