clear
k_noise=0.3;
[x,y,STDY]=xydata(k_noise);
a0=[1 10 0.2 1];						%被估參數(shù)的初始猜測值
options=optimset('lsqnonlin');
options.TolX=0.01;options.Display='off';
a=lsqnonlin(@twoexps3,a0,[],[],options,x,y);
y_est=a(1)*exp(-a(3)*x)+a(2)*exp(-a(4)*x);
a1=num2str(a(1));a2=num2str(a(2));a3=num2str(a(3));a4=num2str(a(4));
char_y_est=['yest=',a1,'*exp(-',a3,'*x) + ',a2,'*exp(-',a4,'*x)'];
disp(['原方程  ', 'y=3*exp(-0.4*x)+12*exp(-3.2*x)'])
disp(['估計方程',char_y_est])