Hi Kennard,
To calculate the exponential Fourier Series, you can make use of the fit function from the Curve Fitting Toolbox. This lets you to fit your fourier model in terms of trignometric equations.
Additionally, there is a file exchange submission for computing Fourier series approximations in a very straightforward manner: https://www.mathworks.com/matlabcentral/fileexchange/31013-simple-real-fourier-series-approximation
