# Sel'kov's model for glycolysis   ch4-selkov.ode 
# See Chapter 4.4.3 (Nullclines and Trapping Regions) in our textbook for details.

dx/dt = rho-sigma*x-x*y^2
dy/dt = -y+sigma*x+x*y^2

# Set the default values of the parameters:
# Don't put spaces between the parameter name, the equal sign, and the parameter value!
par sigma=0.2,rho=0.75

# Set the default initial conditions:
init x=1.0  y=0.5

# Set the default axes for a phase plane plot of y versus x: 
@ xplot=x, yplot=y

# Set the default stopping time and time step
@ total=20, dt=0.01

# Set the default viewing window
@ xlo=0.0,xhi=2.5,ylo=0.0,yhi=2.5
done