I'm trying to use fit the data using this equation:
gaussFit = @(beta, stepFit) (beta(1).*(( ((stepFit./beta(2)).^4)/(1+((stepFit./beta(2)).^4))).*exp((-1).*(stepFit./beta(3))).*cos( (((2*pi).*stepFit)./beta(4)) + beta(5))));
initials = [-0.000006, 0.07, 0.06, 0.12, 0.15];
coeffs = lsqcurvefit(gaussFit, initials, stepFit, avgSPResp2);
But it is giving me a staight line (which I'm guessing is because the initials are way off compared to the actual fit parameters. However, I've tried to estimate the parameters as much as possible looking at the data.
How do I address this issue?