Hi, i need adjust curves with more than two variables. Is it possible? i looked many documentation of MATLAB, but nothing really helped me to achieve this.

I have many data variables and i need adjust curves. i want to know a method that allow adjust a function with more than two data changing at the same time. It is not a simple function, is not one polynomial or linear, has exponencias and several terms, which all vary with time, and I need to find a constant. Please, if you can help me, answer my question! :)

Answer 1

[Star Strider]

The polyfit function and its friends is probably what you want. There are several other options, depending on what you want to do.

[Bruna de Lima]

Hi, Star Stride! I Believe That a polifit will not help me, because my adjust is complex. I saw that i have to use the optimization toolbox , but the documentation makes not clear how should I wear, you know something about it ? thanks for your answer!

[Image Analyst]

Bruna, you're not giving out any information for anyone to work with so there's no way to give a quality answer until you read this link and fix your post.

[Star Strider]

@Image Analyst — Thank you.

@Bruna — I would use the lsqcurvefit function. It will be easier for us to help you if, as Image Analyst said, you tell us more about your model, your data, and what you want to do.

[Image Analyst]

Maybe you want to fit a function to some data and a 2D polynomial fit like John's polyfitn() might work http://www.mathworks.com/matlabcentral/fileexchange/?term=authorid%3A679

Or maybe you want to use scatteredInterpolant(). Why don't you share your data (diagram, figure, image, table, etc.) and let us know what kind of model you want to fit to it?

[Bruna de Lima]

I set a Function with two Variables using surface fitting, and now I have another function with More than two variables and i don't know How i will adjust this. I need to know a method that allow adjust a function with more than two data changing at the same time. It is not a simple function , is not one polynomial or linear, has exponencias and several terms, which all vary with time, and I need to find a constant. This adjustment is a real experiment at a university here in Brazil. Do you understand now what I need to do? do you need to know something more to be able to help me?.t Thank you for your attention! :)

[Star Strider]

With such a general description, we can only give general replies. So no, we do not understand what you need to do, at least in enough detail to provide any sort of definitive reply.

I suggested using the lsqcurvefit function (Optimization Toolbox) earlier. I do not have the Curve Fitting Toolbox, since I don’t need it with the others I have. If you are using it and need help with its functions, I cannot help you.

[Bruna de Lima]

Ok Star Strider! thank you for trying to help :)

[Star Strider]

My pleasure!