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duandian12

木虫 (小有名气)

[求助] 求拟合指点

烦大神们帮帮忙,我有数据x=2.822E-4,0.00495,0.00995,0.0197,0.03985,0.06047,0.07989,0.10009,0.14979,0.20018,0.24984,0.29978,0.39984,0.5003,0.60034,0.70045,0.79981,0.89997,0.99995,1.09996,1.19987,1.29989,1.40027,1.50004,1.59983,1.69939,1.79978,1.89995

y=7.5E-6,6.71875E-4,0.00391,0.0106,0.023,0.0358,0.04649,0.05719,0.08382,0.10749,0.13196,0.15581,0.20194,0.24542,0.2914,0.33464,0.37335,0.42031,0.46305,0.50221,0.54497,0.58705,0.62944,0.66904,0.71459,0.75343,0.79638,0.83817

想用方程y=y0*x*((1-y/y0)^a)*b*exp(-c/2311.3)进行拟合,求出参数y0,a,b,c。跪求各位支下招,小弟不胜感激..........
clc; clear
A=[...
2.822E-4  7.5E-6
0.00495  6.71875E-4
0.00995  0.00391
0.0197  0.0106
0.03985  0.023
0.06047  0.0358
0.07989  0.04649
0.10009  0.05719
0.14979  0.08382
0.20018  0.10749
0.24984  0.13196
0.29978  0.15581
0.39984  0.20194
0.5003  0.24542
0.60034  0.2914
0.70045  0.33464
0.79981  0.37335
0.89997  0.42031
0.99995  0.46305
1.09996  0.50221
1.19987  0.54497
1.29989  0.58705
1.40027  0.62944
1.50004  0.66904
1.59983  0.71459
1.69939  0.75343
1.79978  0.79638
1.89995  0.83817];
format short g
x=A(:,1);y=A(:,2);
X=[x,y];
%y=y0*k0*x*((1-y/y0)^a)*exp(-H/2311.3)
%y0=a(1),k0=a(2),a=a(3),H=a(4)
fun=inline('a(1)*a(2)* x(:,1)*((1- x(:,2)/a(1)).^a(3))*exp(-a(2)/2311.3)-x(:,2)','a','x')
a=nlinfit(x,y,fun,[1 1 1 1])
%{
figure(1)
plot(x,y)
figure(2)
semilogy(x,y)
figure(3)
loglog(x,y)

%}
不知怎么回事就是不对,麻烦指点一下
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