I understand that you want to plot 3 periods of the signal and obtain its Fourier Series.
t = [-pi:0.1:0 0:0.1:pi];
z = [-pi:0.1:0 ones([1, numel(0:0.1:pi)])];
t3 = [t t(2:end)+2*pi t(2:end)+4*pi];
z3 = [z z(2:end) z(2:end)];
plot(t3,z3)
ylim([-pi, pi])
xlim([-pi, 5*pi])
grid on
You can obtain Fourier series coefficients of a signal by using fit function in our Curve Fitting Toolbox or by using Curve Fitting App.
f = fit(t3',z3', 'fourier8');
plot(f, t3, z3)
You can find the fourier coefficients and their values with coeffnames and coeffvalues functions.
You can access the following documentation for further understanding:
- Fourier Series - https://www.mathworks.com/help/curvefit/fourier.html
- Fit function - https://www.mathworks.com/help/curvefit/fit.html
