plotting a phase portrait of non-linear autonomous ODE's using phaseR

phase_portrait.R

if (!require(phaseR)){
    install.packages('phaseR')
    require(phaseR)
}

# a system of two non-linear autonomous ODE's
ode = function (t, y, parameters) {
    x <- y[1]
    y <- y[2]
    dy <- numeric(2)
    dy[1] <- x-x*y
    dy[2] <- y+2*x*y
    list(dy)
}

ode.flowField  <- flowField(ode, x.lim = c(-5, 5), y.lim = c(-5, 5), points = 21, add = FALSE)
ode.nullclines <- nullclines(ode, x.lim = c(-5, 5), y.lim = c(-5, 5), points = 200)
# p14.trajectory <- trajectory(p14, t.end = 10, n=2)