Storing ODE Event values that are within a for loop

Question

SP 2018-1-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/377776-storing-ode-event-values-that-are-within-a-for-loop

编辑： SP 2018-1-18

I have created an ode event as

options = odeset('AbsTol',1e-15,'RelTol',1e-13,'Events',@eventfunction);
[t,y,te,ye,ie]=ode45(@Equations(t,y),0:time,[a0,b0,c0,d0],options);
function [value, isterminal,direction]=eventfunction(t,y)
    value=y(1)+y(2)-1;
    isterminal=1;
    direction=0;

For a particular parameter set outputs for 'te' and 'ye' are

te =

1.8555e+03

ye =

   1.0e+06 *
    0.0000    0.0000    0.0000   10.0000    0.0000

In here I don't understand how I get several 'ye' values for one 'te' value? When I plot the solutions the value in which the condition is met is the first value in 'ye' and this is what I am interested in.

What I am trying to do is a sensitivity analysis and for that, I am changing the parameters at a range of values and for each parameter set I want to find the 'te' and 'ye' values that first meet the condition y(1)+y(2)=1 and store these 'te' and 'ye 'values that are obtained at each 'i'th iteration in the for loop in an array.

For this I defined as

a=zeros(1,1000);
b= zeros(1,1000);

and then within the for loop I tried to do as

a(i)=te
b(i)=ye

But then I get an error as index exceeds matrix dimensions and when I tried as b(i)=ye(1) I get an error as "In an assignment A(:) = B, the number of elements in A and B must be the same."

How can I store in each iteration the first time and the value that the event y(1)+y(2)=1 is satisfied?

For some of these parameters it is possible that the ye and te may be empty. That is it may never be y(1)+y(2)=1. When that happens I want 'te' to be set to very large value as 10^5 and 'ye' to be NaN.

Can someone please help me to obtain these 'te' and 'ye' values in each loop iteration.