how to use lsqnonlin to solve conditional equation
1 回表示 (過去 30 日間)
古いコメントを表示
i would like to input the following equation in matlab and use lsqnonlin to find the C0, Cinfi1, k1, t2start, Cinfi2 and k2 that can fit an obriginal data?
Are there anyone knowning how to do that?
0 件のコメント
採用された回答
Fabio Freschi
2021 年 9 月 7 日
編集済み: Fabio Freschi
2021 年 9 月 7 日
The following code should be self explainatory. In the opposite case, simply ask
clear all, close all
% some dummy params values
C0 = 2;
Cinf1 = 10;
k1 = 2;
t2start = 3;
Cinf2 = 8;
k2 = 3;
% t vector
tData = linspace(0,10,50);
% data + noise
rng(0); % for reproducibility
yData = C0+Cinf1*(1-exp(-k1*tData))+(tData >= t2start).*(Cinf2*(1-exp(-k2*(tData-t2start))))+0.3*randn(size(tData));
% anonymous function for fitting (function-data) that must be minimized
% using least squares
% x(1) = C0
% x(2) = Cinf1
% x(3) = k1
% x(4) = t2start
% x(5) = Cinf2
% x(6) = k2
C = @(x)x(1)+x(2)*(1-exp(-x(3)*tData))+(tData >= x(4)).*(x(5)*(1-exp(-x(6)*(tData-x(4)))))-yData;
% initial values (experience may help here)
x0 = [1 1 1 1 1 1];
% fitting
x = lsqnonlin(C,x0);
% plot
figure, hold on
plot(tData,yData,'o');
% reconstruction of the best fit from the anonymous function
plot(tData,C(x)+yData);
legend('data','best fit');
その他の回答 (0 件)
参考
カテゴリ
Help Center および File Exchange で Fit Postprocessing についてさらに検索
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!