MATLAB Answers

Event Detecting in Event-based ODE

조회 수: 1(최근 30일)
Mostafa Nazmi
Mostafa Nazmi 2021년 6월 11일
댓글: Bjorn Gustavsson 2021년 6월 14일
Greetings. I'm trying to detect an event of a variable value crossing tha value of zero. The problem I'm facing is that the ode solver is detecting the value at 0.1*(1.0e-14) instead of zero. I'm using ode45 and the odeset options below:
ODEopts = odeset('Events', @event, 'Refine', 8, 'RelTol',...
10^-6, 'AbsTol', 10^-6);
Can I solve this issue by changing the options or the solver?
Thanks in advance

채택된 답변

Bjorn Gustavsson
Bjorn Gustavsson 2021년 6월 11일
In order to advice the contents of the event-function is necessary. The only thing to point out is that the ode-solvers use numerical precision of 32-bit(?) doubles - and 1e-14 look like a "reasonable default" setting of zero-detection. If your use-case is something on atomic scales and you use metres as units for your spatial coordinates (convert to what is sensible to your case) then 1e-14 m is clearly not a good enough precision for an event, but ode45 wouldn't know. Your easiest way forward is then to rescale the ODEs to use Å for your spatial coordinates.
HTH
  댓글 수: 2
Bjorn Gustavsson
Bjorn Gustavsson 2021년 6월 14일
Happy to have helped.

댓글을 달려면 로그인하십시오.

추가 답변(0개)

제품


릴리스

R2020b

Community Treasure Hunt

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

Start Hunting!

Translated by