The error lies in the line of
myfittype = fittype("A*cos(omega_0*t+phi)",dependent="A" "omega_0" "phi",independent="t",coefficients=["A" "omega_0" "phi"]);
The following error message appears:
File: TOungedsurfacefit.m Line: 15 Column: 58
Invalid use of operator.
I added a semicolon as suggested in the line error fix message, but it didn't change anything the datatype of s & t is doubles & they are both 400x1 matrices aka vertically imported column vectors in the workspace. Also I saw, that there was a missing closure bracket, but I added that too & still the error occurred. How to proceed? I would be grateful for any further help! I am a beginner in matlab and dont know anything unfortunately.
p=pi;
T= 3.95;
omega_0 = (2*p)/T;
fo = fitoptions('Method','NonlinearLeastSquares','Lower',[-500,500],'Upper',[Inf,max(s)],'StartPoint',[-500,500]);
%alternative:fo = fitoptions('Method','NonlinearLeastSquares','Lower',[-500,500],'Upper',[Inf,max(s)],'StartPoint',[-500,500]);
x = t;
y = s;
myfittype = fittype("A*cos(omega_0*t+phi)",dependent="A" "omega_0" "phi",independent="t",coefficients=["A" "omega_0" "phi"]);
myfit = fit(t',myfittype);
plot(myfit,t);
xdft = fft(t);
camp = 2/length(t)*xdft(t);
phi = angle(camp);
A= abs(camp);
In general, t is the x value & s is the y value accordingly. I have imported the data table as column vectors.
You are using MATLAB's named arguments and string types, which are not the most standard use of MATLAB (not your fault, you are using the docs).
The correct syntax is:
myfittype = fittype("A*cos(omega_0*t+phi)",dependent=["A", "omega_0", "phi"],independent="t",coefficients=["A", "omega_0", "phi"]);
When in doubt, always add the commas and brackets around arrays.
This still errors because you can't use A for both a coefficient and a dependent variable.