Obtaining The Co-Ordinate of Point with minimum value of a Expression

Hi All,

I have an 3D geometry. In the 3D geometry, I have a curve PQRST in ZX- Plane (Image attached). I want to calculate the value of a perticular expression (Say, EXR1), at each point of the curve PQRST. Then I want to locate the coordiane to the point having minimum or maximum value of the expression EXR1.

Thanks in Advance.