fdtd simulation, plotting with gnuplot, writting in perl

# 9月13日 于成都黄龙溪
 1 #!/usr/bin/perl

 # Author : Leon  Email: yangli0534@gmail.com
 # fdtd simulation , plotting with gnuplot, writting in perl
 # perl and gnuplot software packages should be installed before running this program

 #use Time::HiRes qw(sleep);
 #use autodie qw(:all);
 print "\@\n";
 my $terminal = "";
     open GNUPLOT_TERM, "echo 'show terminal;' | gnuplot 2>&1 |";
     while (<GNUPLOT_TERM>) {
     if (m/terminal type is (\w+)/) {
         $terminal=$;
     }
     }
     close GNUPLOT_TERM;

     # unfortunately, the wxt terminal type does not support positioning.
     # hardcode it...
     $terminal  = "x11";

 open my $PIPE ,"| gnuplot " || die "Can't initialize gnuplot number \n";

 print $PIPE "set size 0.85, 0.85\n";
 print $PIPE "set term png size 600, 400\n";

 my $title = "fdtd simulation by leon,yangli0534\\\\@"."gmail.com";
 print $PIPE "set terminal gif animate\n";# terminal type: png
 print $PIPE "set output \"fdtd_simulation_v0.1.gif\"\n";#output file name
 print $PIPE  "set title \"{/Times:Italic $title}\"\n";# title name and font
 #print $PIPE  "set title  \"fdtd simulation by leon,yangli0534\\\\@ gmail.com\"\n";# title name and font
 print $PIPE  "set title  font \",15\"  norotate tc rgb \"white\"\n";
 print $PIPE "unset key\n";
 print $PIPE "set tics textcolor rgb \"white\"\n";# text color
 print $PIPE "set border lc rgb \"orange\"\n";
 print $PIPE "set grid lc rgb\"orange\"\n";
 print $PIPE "set object 1 rectangle from screen 0,0 to screen 1,1 fc rgb \"gray10\" behind\n";#background color
 print $PIPE "set xlabel\" {/Times:Italic distance: wave length}\" tc rgb \"white\" \n";# xlabel
 print $PIPE "set ylabel\"{/Times:Italic amplitude: v}\" tc rgb \"white\"\n";#ylabel
 print $PIPE "set autoscale\n"; 

 my $size = ;#physical distance
 my @ez;#electric field
 my @hy;#magnetic field

 my $imp0 = 377.0;
 #initalization
 for (my $i = ; $i < $size; $i++){
     $ez[$i] = ;
     $hy[$i] = ;

 }
 my $qTime;
 my $MaxTime = ;
 my $pi = 3.141592563589793;
 print $PIPE "set xrange [0:$size-1]\n";
 my $mm = ;

 #do time stepping
 for($qTime = ; $qTime < $MaxTime; $qTime+=){

     # update magnetic field
     for( $mm = ; $mm < $size - ; $mm++){
         $hy[$mm] = $hy[$mm] + ($ez[$mm+] - $ez[$mm])/$imp0;
     }

     # update electric field
     for( $mm = ; $mm < $size ; $mm++){
         $ez[$mm] = $ez[$mm] + ($hy[$mm] - $hy[$mm-])*$imp0;
     }

     if($qTime %  == ){

         print $PIPE "plot \"-\" w l  lw 3 lc rgb \"green\"\n";
         my $cnt = ;
         for my $elem ( @ez) {
         #print " ".$elem;
             print $PIPE $cnt." ".$elem."\n";
             $cnt += ;
         }
         print $PIPE "e\n";
     }
     #hardwire a source
     $ez[] = exp(-($qTime - 30.0)*($qTime - 30.0)/);
 }

 #print $PIPE "set terminal x11\n";

 print $PIPE "set output\n";

 close($PIPE);