i tried to solve differential equations with variable parameter (p).
y''[t] == (1/(p*p))*x[t],
x'[t] == -y'[t] - x[t] + u,
the problem is that when x[t] reaches some value (0 or 4) the sign of u changes like that :
when x[t+1]>x[t] so u=10 until x[t]=4
when x[t+1]<x[t] so u=-10 until x[t]=0
for that i used EvnetLocator Method but it seems like that the event doesn't occure.
Thanks in advance.
Attachment: eventlocator.nb, URL: ,