Change parameter value during ode15s solution
3 Ansichten (letzte 30 Tage)
Ältere Kommentare anzeigen
gorilla3
am 23 Aug. 2018
Kommentiert: gorilla3
am 23 Aug. 2018
Hi,
I'm solving a set of differential equations and I'd like to change the value of a constant (Pin) at a specific time during the solution. Meaning that during the timespan, I'd like to change the value of Pin. So it time>10, Pin=70, else Pin=60.
This is how I formulated it but it's not working:
tspan=0:0.1:100;
cond= [...];
[t,y] = ode15s(@fun2,tspan, cond,[]);
function dydt= fun2(t,y)
for i=1:1:length(tspan)
if tspan(i)<10
Pin=60;
else
Pin=70;
end
end
...
end
0 Kommentare
Akzeptierte Antwort
Torsten
am 23 Aug. 2018
function dydt= fun2(t,y)
...
if t<10
Pin=60;
else
Pin=70;
end
...
Better use the EVENT-facility of the ODE solvers than the if-construction.
Best wishes
Torsten.
3 Kommentare
Steven Lord
am 23 Aug. 2018
In this case I wouldn't use the events functionality. I tend to recommend that when you don't know at write-time when the events you're looking for will occur. In this case, you know exactly when it will occur: at t = 10.
Therefore I'd solve this problem twice. The first call to ode15s would solve from t = 0 to t = 10. I'd use the final result of that call to generate the initial conditions for the second call to ode15s, running from t = 10 to t = 100. Doing so would be easier with a slightly different function signature:
function dydt= fun2(t,y,Pin)
and specifying an anonymous function as the ODE function.
@(t, y) fun2(t, y, desiredValueOfPinForThisOde15sCall)
Replace desiredValueOfPinForThisOde15sCall with 60 or 70 depending on whether you're passing this anonymous function into the first or second ode15s call.
Weitere Antworten (0)
Siehe auch
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!