Monotonically increasing segment F

[hnngaf]

Hello,

   I'm using the SplineController class to navigate a spline with constant speed. While the object is on a specific segment I want to get the local segment F and drive some other system with it and I want the F to move at constant speed between 0 and 1 on the segment. I'm using SplineController.Spline.TFToSegment to get the local F.
   The problem is the sampled local F values form a curve like this, when plotted, instead of a straight line:


   Is there any way to get a monotonically increasing local F?

Thanks