function f = curvefun(x, tdata)

 f = x() + x()*exp(0.02 * x() * tdata);

 %其中x() = a; x() = b; x() = c;

 %数据输入

 tdata = ::;

 cdata = 1e- * [4.54, 4.99, 5.35, 5.65, 5.90, 6.10, 6.26, 6.39, 6.50, 6.59];

 %设定预测值

 x0 = [0.2 0.05 0.05];

 %非线性拟合函数

 x = lsqcurvefit('curvefun', x0, tdata, cdata)

 %作图

 f = curvefun(x, tdata)

 plot(tdata, cdata, 'k+')

 hold on

 plot(tdata, f, 'r')

 function f = curvefun1(x)

 %curvefun1的自变量是x，cdata和tdata是已知参数，故应将cdata,tdata的值卸载curvefun1中

 tdata = ::;

 cdata = 1e- * [4.54, 4.99, 5.35, 5.65, 5.90, 6.10, 6.26, 6.39, 6.50, 6.59];

 f = x() + x()*exp(0.02 * x() * tdata) - cdata;%注意

 tdata = ::;

 cdata = 1e- * [4.54, 4.99, 5.35, 5.65, 5.90, 6.10, 6.26, 6.39, 6.50, 6.59];

 %预测值

 x0 = [0.2 0.05 0.05];

 x = lsqnonlin('curvefun1', x0)

 f = curvefun1(x)

 plot(tdata, cdata, 'k+')

 hold on

 plot(tdata, f+cdata, 'r')