comment on

hello
i am running winxp with perl 10, and have tried to run gnuplot to output the plot to the tkcanvas , i have used zentara example here http://www.perlmonks.com/?node_id=592246 to produce a nice picture http://img695.imageshack.us/img695/3775/plot.jpg, the code is listed below,
just 3 problems, in the first run of the program i have an error message :""Use of uninitialized value in subroutine entry at "" ie about the line "$gnuplot->($canvas);"
in the second run the program run without problems; it seems it is running the previous created plot.pl.
second problem: is that once exited the gnuplot still running in memory; how to close it and all the processes.
the third problem: it seems that the tkcanvas can't display 3D plots such as plotting "splot sin(x*y/20)\n"

#!/usr/bin/perl
use warnings;
use strict;
use Tk;
use Tk::ROText;
use IPC::Open3;

$|++;

my $mw = MainWindow->new;
my $canvas = $mw->Canvas(
                  -bg => 'white',
          -height =>400,
          -width =>500,
          )->pack();


my $button = $mw -> Button(-text => "Quit", 
        -command => \&quit)->pack(-side=>'left');
                                

my $text = $mw->ROText(-bg=>'white')
     ->pack( -fill => 'both', -expand => 1 );

$text->tagConfigure( 'red', -foreground => 'red' );

my $pid = open3( \*IN, \*OUT, \*ERR, "c:/gnuplot/bin/gnuplot.exe" ) ||
+ die;
$mw->fileevent( \*OUT, readable => \&read_out );
$mw->fileevent( \*ERR, readable => \&read_err );

print IN "set term tkcanvas perltk interactive\n";
print IN "set output \'plot.pl\'\n";
#print IN "a=1\n";
#print IN "plot a\n";
#print IN "plot sin(x)/x\n";
#print IN "splot sin(x*y/20)\n";
print IN "plot sin(x) title 'Sine Function', tan(x) title 'Tangent'\n"
+;
my $gnuplot = do "plot.pl";

$gnuplot->($canvas);

MainLoop;

sub read_out {
}

sub read_err {
    print "read_err()\n";
    my $num = sysread(ERR, my $buffer, 1024 );
    $text->insert( 'end', $buffer, 'red' );
}

sub quit{close $pid; exit}
[download]

on the other hand in the same zentara page there is a second solution to plot the graphic directly to the canvas, i was not able to run the code ,just the canvas without plot, the same is the superformula example http://www.perlmonks.com/?node_id=592338 i got an error message (open3: Can't locate auto/Tk/ROText/FILENO.al in @INC (@INC contains: c:/perl/sit e/lib c:/perl/lib .) at c:/perl/site/lib/Tk/Derived.pm line 469 ) related to the presence of "tie(*STDOUT, 'Tk::Text', $text);" i wish zentara or someone to make those examples available for windows systems, thanks
at last i have found a nice example in the book "Gnuplot in Action" to run gnuplot from perl: it is directing the output to graph.png file http://img412.imageshack.us/img412/1378/grapht.png

open PROC, "| c:/gnuplot/bin/gnuplot.exe" || die "Could not start gnup
+lot: $!";
#above :the first character in the filename is a pipe symbol (|)
print PROC "set xlabel 'Time'; set ylabel 'Amplitude';";
print PROC "set o 'graph.png';";
print PROC "set t png;";
print PROC "plot '-' u 1:2 t 'data' w l\n";
for( $x = 0.0; $x <= 10.0; $x += 0.1 ) {
$y = exp(-$x/5)*sin( $x );
print PROC "$x $y\n";
}
print PROC "e\n";
close PROC;
[download]

thanks for your patience

In reply to gnuplot output to tkcanvas by tallulah

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