Scatter chart lines

[Fred]

I am trying to find out how excel creates the smooth line used to join
points in a scatter chart.
Does anyone know the formula used.
Any help is much appreciated. Thanks

Fred

 

[Milos Setek]

Hi Fred,
I would say that this is a Microsoft secret. Some people have wandered about
this before.
It is probably some sort of cubic-spline curve.
Regards,
Milos