Hill functions. Shapes of the Hill function for different values of the parameters. The solid red line is a Hill function with parameters θ=0.5 and μ=5. The shaded red area is the family of Hill functions obtained when θ∈[0.3,0.8] and μ is fixed. Similarly, the solid blue line is the Hill function of parameters θ=0.3 and μ=6. The shaded blue area is the family of Hill functions obtained when μ∈[2,10] and θ is fixed.