What toolbox/function do I use?

Hi

What toolbox/function do I use to Convert (x,y,z) data into a function y => f(x,z).

I need a nonlinear equation because the (x,y) data has an exponential relationship.

Thank you

[Rik]

Have you tried your favorite internet search engine?

Have a read here and here. It will greatly improve your chances of getting an answer.

[Walter Roberson]

Do you already know what the form of the relationship is, but you just need to find the best match of coefficients from your experimental data? Is it necessary that the function exactly match the experimental data (to within round-off error), or are you considering the data to possibly have noise?

[Patrick Lanard]

I am fine if the coefficients give me ballpark of the real values (+-10%)!

[Image Analyst]

But what is the model? Is it y = ax^b + c*exp(d*z)? Probably not. Maybe it's y = exp(-a*x^2 + b*z^2)? Ok, probably not that either. Do you have some other form? You need to guess at a model and then MATLAB can get the unknown parameters.

For what it's worth, attached are some non-linear fit demos.

[Patrick Lanard]

I don't know what the model is! Still, work in progress. Thank you for the information.