[R-sig-dyn-mod] Modeling dampened oscillator with random resets

[Thomas Petzoldt]

On 09.01.2013 15:33, Felix Schönbrodt wrote:
> Dear list,
>
> using deSolve (or another package): is it possible to model a
> dampened oscillator that is reset to new states at specific points?

Yes, this is possible, using the event mechanism:


library(deSolve)
osci <- function (t, states, parms) {
   with(as.list(c(states,  parms)), {
     dx <- y
     dy <- eta * x + zeta * y
     list(c(dx, dy))
   })
}

states <- c(x = 1, y = 0)
out <- ode(states, osci, times = 1:200,
   parms = c(eta = -0.05, zeta = -0.02))
plot(out)


###  see ?events for details
eventdat <- data.frame(var = "y", time = c(70, 120),
                        value = c(0.7, 1), method = "add")

out <- ode(states, osci, times = 1:200,
   parms = c(eta = -0.05, zeta = -0.02),
   events = list(data = eventdat))
plot(out, which = "y")
abline(v = eventdat$time, col = "red", lty = "dashed")




## Thomas P.