(Curve fitting) fitting a specific equation to experimental data

2012 3 2
1 个回答
2 次查看（30 天）

1 个投票

Dear all, I have several experimental data and I know the governing nonlinear equation of these data. Now I am trying to find constants/parameters in this equation. But there are 5 unknowns in this equation. Thanks Best regards Victor

请先登录，再回答此问题。

回答（1 个）

Andrei Bobrov
Andrei Bobrov 2012-3-2

2 个投票

try nlinfit

3 个评论
显示 1更早的评论 隐藏 1更早的评论

Victor
Victor 2012-3-2
Dear Andrei,
Thanks for your comment.
May I ask you to have a look to the example in:
http://www.mathworks.co.uk/help/toolbox/stats/nlinfit.html
I can not understand the role of part 2: "Generate synthetic data with parameters a = [1;3;2]". Do you have any idea what is the concept behind it?
It is a little bit puzzling for me.
Thanks
Victor
Victor 2012-3-2
Dear Andrei,
Thanks.
May I ask you to follow this simple example. it gives me strange error!
clc
clear
%Suppose matrix of X is experimental data and is composed of x' and y' and matrix a is unknown
%parameters and the known equation is yi = a1 + a2exp(–a3xi)
mdl = @(a,X)(X(:,2)-a(1) + a(2)*exp(-a(3)*X(:,1)));
%arbitrary guess a0 = [2;2;2]:
a = [1;3;2];
x = [0,10,20];
y= [0,5,10];
X=[x',y'];
func = mdl(a,X) ;
a0 = [2;2;2];
[ahat,r,J,cov,mse] = nlinfit(x,y,mdl,a0);
ahat

请先登录，再进行评论。

类别

在 帮助中心 和 File Exchange 中查找有关 Linear and Nonlinear Regression 的更多信息

标签

提问:

Victor
Victor
2012-3-2

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!

Translated by