' h3blib.bas - jackord@kw.igs.net - revised 10 Sep 02 - Liberty Basic v3.01
' period of a pendulum with 90 degree amplitude
  g=9.8: L=9.8: pi=4*atn(1): sm=L*pi/2
  n=400: ds=2*sm/n
  t=0: v1=0
  for i=1 to n-1
    s=sm-i*ds: v2=(2*g*L*(cos(s/L)-cos(sm/L)))^.5
    t=t+2/(v1+v2): v1=v2
  next i
  t=2*(t+2/v1)*ds
  print "90 deg amplitude Tvbar = "; t
  dt=.01
  t=0: s=sm: v=0: a=0-g*sin(s/L)
  v=v+a*dt/2
  while v<0
    t=t+dt: s=s+v*dt: a=0-g*sin(s/L): v=v+a*dt
  wend
  t=2*(t+dt/2-v/a)
  print "90 deg amplitude Tfeyn = "; t
  print "Increase over small angle T = "; using("##.#", 100*(t/2/pi-1)); " %"