# file Collins_toggle_switch.ode
# model of Collins toggle switch
# from Gardiner et al. (2000) Nature 403, pp. 339-342
# Figures 1.7, 7.13, 7.14

par a1=3, a2=2.5, beta=4, gamma=4, i1=0, i2=0

#model equations
s1' = a1/(1+(s2/(1+i2))^beta) - s1
s2' = a2/(1+(s1/(1+i1))^gamma) - s2

# initial condition
init s1=0, s2=1

# final time
@ total=4
# set the plotting window size:
@ xlo=0, xhi=4, ylo=0, yhi=4

# run the simulation in the GUI by selecting (I)nitialconds|(G)o
# plot species s2 by selecting (G)raphic stuff|(A)dd curve and 
# assigning the y-axis

#multiple trajectories can be generated by (G)raphic stuff|(F)reeze and
#running simulations from different initial conditions

#generate a phase plane by choosing (V)iewaxis|(2)D and assigning the axis
#the nullclines can be generated with (N)ullclies|(N)ew
#a direction field can be generated with (D)ir.field/flow|(D)irect field

done