#!/usr/bin/perl
#
# Compute a sample potential energy and its associated force
#
# MWR 3/4/2021

use POSIX;
$debug = 1;

$mypi = 3.14159265;


$start_x = 0.01;
$end_x = 12.0;
$d_x = 0.001;
for ($x = $start_x; $x <= $end_x; $x += $d_x) {

  $pe = 10.0*$x*$x*cos($x)*exp(-$x);
  $force = -20.0*$x*cos($x)*exp(-$x) + 10.0*$x*$x*sin($x)*exp(-$x) +
                   10.0*$x*$x*cos($x)*exp(-$x);

  printf "x %8.3f  force %8.3f  pe %8.3f \n", $x, $force, $pe;

}


exit 0;