fsolve in a for loop

Question

Rajeev kamal 2015-12-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/260956-fsolve-in-a-for-loop

评论： Star Strider 2016-1-21

I am trying an analytical solution from nonlinear equation for a transient temperature problem. I call the function as

fun = @funhouse;
x0 = [1,1]';
options = optimoptions('fsolve','Display','iter');
[x,fval] = fsolve(@funhouse,x0,options);

And the function is

function F = funhouse(x,Tain)
Ts=18+273;% in K
Ca=11918;% kJ/K
Hae=52.33;%W/K
Hame=41.26;%W/K
Has=87.43;%W/K
Hag=15.54;%W/K
Htot=Hae+Hame+Has+Hag;
tao=17;%W/K
Te=10+273;
t=1;
tao=17;
%FUNHOUSE Summary of this function goes here
%   Detailed explanation goes here
F = [x(1)-Ca*(x(2)-Tain)-Hae*(x(2)-Te)-Hame*(x(2)-Te)-Hag*(x(2)-Te)-Has*(x(2)-Te);
     x(2)-(Tain-(x(1)/Htot)-(Htot-Has)*Te/Htot-Has*Ts/Htot)*exp(-t/tao)-(x(1)+(Htot-Has)*Te+Has*Ts)/Htot];
end

How to pass Tain as the last value found from the fsolve to the next iteration and save the output in an array.

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Rajeev kamal 2016-1-19

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/260956-fsolve-in-a-for-loop#answer_206706

Modified code to fix Tenv(i) to pass to the funh.m

________________________________________

clear clc Ta=zeros(1,25); t=1; Ta(1)=16+273; Te=[9 12 10 10 18 18 11 11 11 11 12 16 16 18 18 20 20 15 15 13 13 12 12 10 9 9 12 10 10 10 10 11 11 11 11 12 16 16 18 18 20 20 15 15 13 13 12 12 10 9 9 12 10 10 10 10 11 11 11 11 12 16 16 18 18 20 20 15 15 13 13 12 12 10 9 9 12 10 10 10 10 11 11 11 11 12 16 16 18 18 20 20 15 15 13 13 12 12 10 9]'; P=ones(1,25); x0(2)=293; x0(1)=6; for i=2:100 % fun = @funh; Tain=Ta(i-1); Tenv(i)=Te(i)+273; options = optimoptions('fsolve','Display','iter') [xopt,Fval,exitflag] = fsolve(@(x)funh(x,Tain,Tenv(i)),x0,options) Ta(i) = xopt(2); % Tain=xopt(2); xsav(i,:) = xopt; end i=1:1:100; plot(i,xsav(:,1),i,xsav(:,2));

------------------- Now I am getting the Ta as almost constant for all iterations while the xsav(1) fluctuated to negative and positive values. The expected values should be positive real for xsav(1) while xsav(2) should give more fluctuation. @star strider I am not familiar with patternsearch and neither the Matlab help recognizes this.