Curve fitting for a trig function

Hi I want to fit a trig function, and get the R^2 value for a graph that I have already plotted, the data are voltage measurements vs. time and each column has around 360 data. I tried using the basic fitting feature under tools of the plot window, but it seems like its just for polynomial functions. Thanks, Hannah

Answer 1

[the cyclist]

If you have the Statistics Toolbox, you can use the nlinfit() function to do this.

[Yalda]

Is there any other way of doing it? I don't have statistic toolbox now, I have ordered one though, but will probably take me two or 3 days to get it.

Answer 2

[Shashank Prasanna]

You can do custom fitting using optimization functions from base MATLAB.

Here is a page from the documentation that shows you how to go about doing it:

http://www.mathworks.com/help/matlab/math/example-curve-fitting-via-optimization.html

If you'd like goodness of fit statistics then you will have to manually compute them using the relevant formulae. If you plan on using the Curve Fitting Toolbox or the Statistics Toolbox then you get them for free.