#! /bin/sh
# sm.energy.kep -- plot energy conservation for Kepler orbits

ydot=$1
wait=$2

type='kep'
label='Kepler Potential, \dot{y}_i='$ydot

date=`date '+%D %H:%M'`

sm -s << FIN
if ($wait) {xterm_p} else {laser_pp 'energy.kep.ydot$ydot.ps' \n lweight 2}
expand 0.85
macro plt 2 {
  sixwin \$1
  read {t 1 de 6}

  # the following two lines create symmetric y-axis limits that span the
  # range of the vector de
  set xx = de concat (-de)
  limits -1 41 xx

  box
  connect t de
  limits 0 10 0 10
  relocate 0 10.5
  putlabel 6 \$2
  relocate 5 -1.5
  putlabel 5 t
  relocate -2.5 5
  angle 90
  putlabel 5 \Delta E/|E|
  angle 0
}
da $type.ydot$ydot.eul.dt0.01
plt 1 "Euler, dt=0.01"
da $type.ydot$ydot.eul.dt0.0001
plt 2 "Euler, dt=0.0001"
da $type.ydot$ydot.leap.dt0.01
plt 3 "Leapfrog, dt=0.01"
da $type.ydot$ydot.leap.dt0.0001
plt 4 "Leapfrog, dt=0.0001"

ctype 0
expand 1.1
location 5000 29000 22530 30000
limits 0 10 0 10
relocate 5 12
putlabel 5 $label

#putdate "$date"
if ($wait) {!sleep $wait} else {hardcopy}
FIN