BCF model. Temporal alternation

Here we add excitation cI(t) with period T to the BCF system
    du/dt = -(Jfi + Jso + Jsi ) + cI(t),     I(t) ~ [cos(πt/T)]500,     δI(t)dt = 1.

c T Ymax dt it
u, v, w, s variables are black, blue, red and green curves. The script makes 1000 it time steps dt.
Heart rhythms     updated 8 Dec 2011