dv/dt = H(u, v) = ε(u)(ku - v),

where

To the right below *u(t)* excitation (black) and *v(t)*
recovery (blue) variables are plotted.
To the left the *(u, v)* phase plane of the system is shown.
*F(u,v) = 0* null cline is the red line and
*H(u,v) = 0* null cline is the green line.

Below you can explore the model for different parameter values.
The script makes 800 time steps *dt*.

a
k

dt
u0
v0
Ymin
Ymax
field

The system makes excitation cycle and goes to the stable fixed point
*(u=0, v=0)*.

Heart rhythms