#!/usr/bin/perl
#
#

$mypi = 3.14159;

######################################################
#  plot a potential energy as a function of position
  
  my($output_file, $term_options);

  # get the arguments
  $output_file = "calc_f_pe_a.ps";
  $term_options = "postscript color enhanced 'Helvetica,18' ";

  $cmdfile = "gnuplot.in";
  
  open (CMDFILE, ">$cmdfile") || die("can't open $cmdfile for writing");
  printf CMDFILE "set output '$output_file' \n";
  printf CMDFILE "set term $term_options \n";

  # revert to some oldish default colors
  printf CMDFILE "set style line 1 lt rgb 'red' lw 3  \n";
  printf CMDFILE "set style line 2 lt rgb 'sea-green' lw 3  \n";
  printf CMDFILE "set style line 3 lt rgb 'blue' lw 3  \n";
  printf CMDFILE "set style line 4 lt rgb 'cyan' lw 3  \n";
  printf CMDFILE "set style line 5 lt rgb 'violet' lw 3  \n";


  printf CMDFILE "set grid \n";
  printf CMDFILE "set key top right \n";
  printf CMDFILE "set size square \n";
#  printf CMDFILE "set xzeroaxis  lw 3.5 \n";
#  printf CMDFILE "set yzeroaxis  lw 3.5 \n";
  printf CMDFILE "set xlabel 'Position (m)  '  \n";
  printf CMDFILE "set ylabel 'Potential energy (J) ' \n";
#  printf CMDFILE "set title 'Motion of 2-block, 3-spring system: m=2, k=30, 60, 90 ' \n";

  $cmd = "plot [-0:12][-6:6] 'calc_f_pe.out' using 2:6 ";
  $cmd .= "        with lines ls 1 lw 4 t 'PE' ";
#  $cmd .= " , ";
#  $cmd .= "                         'calc_challenge.out' using 2:6 ";
#  $cmd .= "        with lines ls 3 lw 3 t 'right block' ";

  printf CMDFILE "$cmd \n";


  printf CMDFILE "set output \n";
  printf CMDFILE "quit \n";
  close(CMDFILE) ;
  
  $retval = `gnuplot < $cmdfile`;
  printf "retval is ..%s..\n", $retval;
  
  if ($term_options =~ /postscript/) {
    $psfile = $output_file;
    $giffile = $psfile;
    $giffile =~ s/.ps/.png/;
    $cmd = "convert -rotate 90 $psfile $giffile";
    printf "cmd is ..$cmd.. \n";
    $ret = `$cmd`;
  }


######################################################
#  plot the force associated with a potential energy as a function of position
  
  my($output_file, $term_options);

  # get the arguments
  $output_file = "calc_f_pe_b.ps";
  $term_options = "postscript color enhanced 'Helvetica,18' ";

  $cmdfile = "gnuplot.in";
  
  open (CMDFILE, ">$cmdfile") || die("can't open $cmdfile for writing");
  printf CMDFILE "set output '$output_file' \n";
  printf CMDFILE "set term $term_options \n";

  # revert to some oldish default colors
  printf CMDFILE "set style line 1 lt rgb 'red' lw 3  \n";
  printf CMDFILE "set style line 2 lt rgb 'sea-green' lw 3  \n";
  printf CMDFILE "set style line 3 lt rgb 'blue' lw 3  \n";
  printf CMDFILE "set style line 4 lt rgb 'cyan' lw 3  \n";
  printf CMDFILE "set style line 5 lt rgb 'violet' lw 3  \n";


  printf CMDFILE "set grid \n";
  printf CMDFILE "set key top right \n";
  printf CMDFILE "set size square \n";
#  printf CMDFILE "set xzeroaxis  lw 3.5 \n";
#  printf CMDFILE "set yzeroaxis  lw 3.5 \n";
  printf CMDFILE "set xlabel 'Position (m)  '  \n";
  printf CMDFILE "set ylabel 'Force (N) ' \n";
#  printf CMDFILE "set title 'Motion of 2-block, 3-spring system: m=2, k=30, 60, 90 ' \n";

  $cmd = "plot [-0:12][-6:6] 'calc_f_pe.out' using 2:4 ";
  $cmd .= "        with lines ls 3 lw 4 t 'F' ";
#  $cmd .= " , ";
#  $cmd .= "                         'calc_challenge.out' using 2:6 ";
#  $cmd .= "        with lines ls 3 lw 3 t 'right block' ";

  printf CMDFILE "$cmd \n";


  printf CMDFILE "set output \n";
  printf CMDFILE "quit \n";
  close(CMDFILE) ;
  
  $retval = `gnuplot < $cmdfile`;
  printf "retval is ..%s..\n", $retval;
  
  if ($term_options =~ /postscript/) {
    $psfile = $output_file;
    $giffile = $psfile;
    $giffile =~ s/.ps/.png/;
    $cmd = "convert -rotate 90 $psfile $giffile";
    printf "cmd is ..$cmd.. \n";
    $ret = `$cmd`;
  }





exit 0;