chap18.py

from modsim import *

def make_system(params, data):
    G0, k1, k2, k3 = params
    
    t_0 = data.index[0]
    t_end = data.index[-1]
    
    Gb = data.glucose[t_0]
    Ib = data.insulin[t_0]
    I = interpolate(data.insulin)
    
    init = State(G=G0, X=0)
    
    return System(init=init, params=params,
                  Gb=Gb, Ib=Ib, I=I,
                  t_0=t_0, t_end=t_end, dt=2)

from modsim import *

def slope_func(t, state, system):
    G, X = state
    G0, k1, k2, k3 = system.params 
    I, Ib, Gb = system.I, system.Ib, system.Gb
        
    dGdt = -k1 * (G - Gb) - X*G
    dXdt = k3 * (I(t) - Ib) - k2 * X
    
    return dGdt, dXdt