function ss = algaess(theta,data)% algae sum-of-squares functiontime   = data.ydata(:,1);ydata  = data.ydata(:,2:end);xdata  = data.xdata;% 3 last parameters are the initial statesy0 = theta(end-2:end);ymodel = algaefun(time,theta,y0,xdata);ss = sum((ymodel - ydata).^2);