How to fit a curve to the following 3D data?

Hello, I have extracted the data from two graphs. Let's say one is X vs Z with constant Y and the other is Y vs Z with constant X. I have plotted a 3D graph for the same. Now I need a function describing the relation between the 3 variables. I am uploading a sample file along with this question. How do I determine which curve fits the best and the equation for the same?

[James Phillips]

Looking at the data as a 3D scatterplot, it does not appear to be on a smooth surface. Note that the raw data shows a mix of precisions after the decimal point, so this may be an artifact of the extraction process and might be worth a quick review. A preliminary fit to a simple 3D linear polynomial flat plane:

z = a + bx + cy
a =  2.5842576520697861E+01
b = -3.5447221432563505E-03
c = -3.4737788847693296E-02

is attached as a surface plot. Since this is a polynomial you can fit the data as you would any other polynomial equation.

[Essam Ali]

please,did you get the answer?I have the same problem

[darova]

Try fit

Answer 1

[Varun Gunda]

If you have the Curve Fitting Toolbox , you could try interactive surface fitting .

If you don't have it, you could try polyfitn, which you can download from the File Exchange.