# u''+a*u' + b*u = F0*cos(w*t)
u'=up
up'=-a*up-b*u+f0*cos(w*t)
init u=0,up=0
par a=0,b=1,f0=.5,w=.8
# a is the damping, b is the spring constant
# w is the forcing frequency
@ total=80,xhi=80,xlo=0
@ ylo=-5,yhi=5
done