#!/usr/bin/perl
#
#

##########################################
#  plot phase as a function of frequency
#      for a low-damping system
  
  my($output_file, $term_options);

  # get the arguments
  $output_file = "phase_plot_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 '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 bot left \n";
  printf CMDFILE "set ylabel 'Phase (degrees)'  \n";
  printf CMDFILE "set xlabel 'Driving Frequency (rad/s)' \n";
  printf CMDFILE "set title 'F_{max} = 2.0 N, m = 0.1 kg, k = 7.5 N/m, b = 0.02 N/m/s' \n";
  printf CMDFILE "set label  '{/Symbol w_0} ' at 8.5,-5.5 \n";
  printf CMDFILE "set arrow 1 from 8.66,0 to 8.66,180 nohead lt 0 lc -1 lw 3 \n";

  $cmd = "plot [0:20][0:180] './calc_phase.out' index 0 using 2:8 ";
  $cmd .= "        with points ls 1 ps 0.6 pt 3 t '' ";
  printf CMDFILE "$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;


