How to store conditional values during iteration by using Ode45?

Question

Cola 2021-8-27

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1441814-how-to-store-conditional-values-during-iteration-by-using-ode45

评论： Wan Ji 2021-8-27

采纳的回答： Wan Ji

I want to store data of each iteration, including the conditional values. Is there a way to do this? Thanks!

There is an example where 'b' is the conditional value. And the goal ([b0,t,X1]) is as follows:

1 0 1.0000

1 1.0000 1.5378

1 2.0000 1.6115

1 3.0000 1.6175

1 4.0000 1.6180

1 5.0000 1.6180

2 0 1.0000

2 1.0000 1.9317

2 2.0000 1.9987

2 3.0000 2.0000

2 4.0000 2.0000

2 5.0000 2.0000

3 0 1.0000

3 1.0000 2.2584

3 2.0000 2.3036

3 3.0000 2.3028

3 4.0000 2.3028

3 5.0000 2.3028

Code：

save=[]

t0=0;

tf=15;

a0=1

global b0;

for b0=1:1:3

X=[a0]

[t, X1] = ode45(@fun,[t0:0.1:tf], X);

% X2=[b0,t,X1(1)];

X2=[t,X1];

save=[save;X2]

end

function fx=fun(t,x)

fx=zeros(1,1);

global b0

b=b0

fx(1)=x(1)-x(1)^2+b

end

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Answer 1

Wan Ji 2021-8-27

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1441814-how-to-store-conditional-values-during-iteration-by-using-ode45#answer_775459

编辑：Wan Ji 2021-8-27

在 MATLAB Online 中打开

You can define a table to store the data including the conditional values

function main
t0=0;
tf=15;
a0=1;
T = table();
global b0;
for b0=1:1:3
    X=[a0];
    [time, xval] = ode45(@fun,[t0:0.1:tf], X);
    b = b0*ones(size(time));
    T = [T; table(b, time, xval)]; % use table T to store the data
end
writetable(T,'Table.txt')
end
function fx=fun(t,x)
fx=zeros(1,1);
global b0
b=b0;
fx(1)=x(1)-x(1)^2+b;
end