#
# Plot a phase diagram for this differential equation:
#
if( !require('phaseR') ){
    install.packages('phaseR')
}
library(phaseR)

my_yprime = function(t, y, parameters){
    x=y[1]
    y=y[2]
    dy = numeric(2)
    dy[1]=1
    dy[2]=x*y*(3-y)
    list( dy )
}

diff_eq_params = c()

#postscript("../../WriteUp/Graphics/Chapter2/chap_2_sect_4_prob_17_plot.eps", onefile=FALSE, horizontal=FALSE)

flowField(my_yprime, x.lim = c(0, 1), y.lim = c(-6, 6), parameters = diff_eq_params, points = 21, add = FALSE, xlab='t')
trajectory(my_yprime, y0= c(0, 5.5), t.end = 1, parameters=diff_eq_params)
trajectory(my_yprime, y0 = c(0, 1), t.end = 1, parameters=diff_eq_params)
trajectory(my_yprime, y0 = c(0, -1), t.end = 1, parameters=diff_eq_params)

#dev.off()