Hi,

we may discuss this interesting subject through my email [email protected].

From an analytical point of view it is clear how to find for this function of 2 variables the saddle point. See a standard text book/web site on multivariate functions: calculate the Hessian.The only problem I see is that the function variations are very weak, there is an enormous offset that you maybe should subtract for numerical purposes.

I do not remember anymore whether Sigmaplot can do this itself, haven't used it for over 20 years now. In those days it was pretty buggy so I stopped using it.

Thank you sir Ger Koper