# cable equation with different BC's
u0'=d*(u1-u0)+f(u100) - b*u0
u[1..99]'=d*(u[j+1]-2*u[j]+u[j-1])-b*u[j]
u100'=d*(u99-u100)-b*u100
f(u)=tanh(c*u)
par b=.001,d=1,c=-5
done