matlab指数拟合

来源：百度知道 编辑：UC知道 时间：2024/05/16 14:43:20
x=1993:1:2003
y=[0.818691554 0.789061222 0.751629834
0.738927407 0.735678662
0.689186775 0.68293436
0.665770829 0.659170406 0.637114428 0.62024148 ];

如何进行曲线拟合 得到拟合公式 y = a1 + exp(a2*x)
并得出R^2

按常理：按下面操作即可
在Matlab下输入：edit，然后将下面两行百分号之间的内容，复制进去，保存
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
function F=zhidao_fit_4(a,x)
F=a(1)+exp(a(2)*x);
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

在Matlab下面输入：
x=1993:1:2003;
y=[0.818691554 0.789061222 0.751629834 0.738927407 0.735678662 0.689186775 0.68293436 0.665770829 0.659170406 0.637114428 0.62024148];

[A,res]=lsqcurvefit('zhidao_fit_4',0.001*ones(1,2),x,y);
A
结果：
A =

0.7080 -0.0953

但是作图的话，就不好了。
>> yy=zhidao_fit_4(A,x);
>> plot(x,y,'*',x,yy,'r')
差距比较大。
你看一下，你的x是在指数上面的，你的x那么大

建议你：
x=1:11;
y=[0.818691554 0.789061222 0.751629834 0.738927407 0.735678662 0.689186775 0.68293436 0.665770829 0.659170406 0.637114428 0.62024148];

[A,res]=lsqcurvefit('zhidao_fit_4',0.001*ones(1,2),x,y);
A
>> yy=zhidao_fit_4(A,