FitPair:

-------------------------------------------------------------------------------
   Given xF, find yF that best fits xF given the pair (x,y)
   xF may repeat in x. Does a linear interpolation for yF.

   For a demo type FitPair.

-------------------------------------------------------------------------------
   Form:
   yF = FitPair( x, y, xF )
-------------------------------------------------------------------------------

   ------
   Inputs
   ------
   x               (1,:) x values
   y               (1,:) y values
   xF              (1,1) Value to be fit

   -------
   Outputs
   -------
   yF              (1,n) Corresponding y values

-------------------------------------------------------------------------------

Children: