Question

matlab 曲线拟合，求助

函数y=A*(ln(Bx+1))+C;
x f
1 3.15
2 8.25
3 12.51
4 16.16
5 19.37
6 22.22
7 24.78
8 27.12
9 29.26
10 31.24
11 33.08
12 34.79
13 36.40
14 37.92
15 39.35
16 40.71
17 42.00
18 43.22
19 44.40
20 45.52
21 46.59
22 47.62
23 48.62
24 49.57
25 50.50
26 51.39
27 52.25
28 53.08
29 53.89

Answer 1

f=[3.15 8.25 12.51 16.16 19.37 22.22 24.78 27.12 29.26 31.24 33.08 34.79 36.40 37.92 39.35 40.71 42.00 43.22 44.40 45.52 46.59 47.62 48.62 49.57 50.50 51.39 52.25 53.08 53.89]; 

x=[1:1:29];

F=@(p,a)p(1)*log(p(2)*a+1)+p(3);

p=lsqcurvefit(F,[1 1 1],x,f)

y=25.9028*(log(0.2780*x+1))-3.2009;

plot(x,y,'r-',x,f,'ko');

grid on;

最后运行结果为：p = 25.9028    0.2780   -3.2009即y=25.9028*(ln(0.2780x+1))-3.2009; 效果如下图