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 "@
";
my $terminal = "";
    open GNUPLOT_TERM, "echo 'show terminal;' | gnuplot 2>&1 |";
    while (<GNUPLOT_TERM>) {
    if (m/terminal type is (w+)/) {
        $terminal=$1;
    }
    }
    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 
";

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

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

my $size = 400;#physical distance
my @ez;#electric field
my @hy;#magnetic field
 
my $imp0 = 377.0;
#initalization
for (my $i = 0; $i < $size; $i++){
    $ez[$i] = 0;
    $hy[$i] = 0;
     
} 
my $qTime;
my $MaxTime = 1850;
my $pi = 3.141592563589793;
print $PIPE "set xrange [0:$size-1]
";
my $mm = 0;

#do time stepping
for($qTime = 0; $qTime < $MaxTime; $qTime+=5){

    # update magnetic field
    for( $mm = 0; $mm < $size - 1; $mm++){
        $hy[$mm] = $hy[$mm] + ($ez[$mm+1] - $ez[$mm])/$imp0;
    }

    # update electric field
    for( $mm = 1; $mm < $size ; $mm++){
        $ez[$mm] = $ez[$mm] + ($hy[$mm] - $hy[$mm-1])*$imp0;
    }
    
    if($qTime % 10 == 0){

        print $PIPE "plot "-" w l  lw 3 lc rgb "green"
";
        my $cnt = 0;
        for my $elem ( @ez) {
        #print " ".$elem;
            print $PIPE $cnt." ".$elem."
";
            $cnt += 1;
        }
        print $PIPE "e
";
    } 
    #hardwire a source
    $ez[0] = exp(-($qTime - 30.0)*($qTime - 30.0)/100);
}

#print $PIPE "set terminal x11
";

print $PIPE "set output
";

close($PIPE);