###########################################################
#        Fitzhugh Nagumo Travelling wave
#
#             v_t = d v_xx + f(v) - w
#             w_t = e (u- g v)
#
#        Stimulus is constant current "ia" applied at right
#        end, i.e.,
#
#             v_x(0,t) = ia1 = 0        (default)
#             v_x(1,t) = ia2
#
#
###########################################################
SPACE x
TIME t
SET DELTA_T=.1
SET TFINAL=.5
SET GRID=50
SET PLOTVAR=v
SET BUFSIZE=2000
SET RGB=1
SET LENGTH=1
SET METHOD=2
SET FAST=1
SET NOUT=200
#
#     default parameter values (left neumann)
#
PAR ia1=0,ia2=-1,d=0.0005,eps=0.05,a=0.5,gam=1
#
#     axon initially at rest: v(x,0)=w(x,0)=0
#
CVAR v=0
CVAR w=0
#
#    boundary conditions
#
BDRY v 0 leaky {1} {0} {ia1}
BDRY v 1 leaky {1} {0} {ia2}
#
#    PDE definition
#
FUN  f  1 a*(arg1-1/3*arg1^3)
#
v'=d*v_xx+f(v)-w
w'=eps*(v-gam*w)
DONE