f = @(a,t) a(1) + a(2).*sin(2*pi*a(3).*t + a(4)).*(t > a(5)/1000).*(t < a(6)/1000);
a0 = [4.806,1.1,1000,-2.43,5,40];
lb = [4,0, 990,-2*pi,0,1000*t(end)/2];
ub = [6,6,1010, 2*pi,1000*t(end)/2,1000*t(end)];
options = optimoptions('lsqcurvefit','TolX',1E-12,'TolFun',1E-12,'display','iter');
[a,resnorm,resid,exitflag,output,lambda,jacobian] = lsqcurvefit(f,a0,t,y,lb,ub,options);
plot(t,y,':',t,f(a,t),'-','LineWidth',2)
Norm of First-order
Iteration Func-count f(x) step optimality
0 7 7077.56 7.47e+06
1 14 6263.64 0.116348 651
2 21 6253.51 0.0151571 9.82
3 28 6253.51 0.000237627 0.00237
4 35 6253.51 6.05696e-08 3.65e-06
Local minimum possible.
lsqcurvefit stopped because the size of the current step is less than
the selected value of the step size tolerance.
