# bistable equation
par d=1,h=.2,a=.02
u0=u1
u[1..100]'=u[j]*(u[j]-a)*(1-u[j])+d*(u[j+1]-2*u[j]+u[j-1])/(h*h)
u101=u100
init u[1..4]=1
@ dt=.025,total=40
done