#!/usr/bin/perl -w

# The Integral of the mathematical function 1/x

use strict;
use Chart::Bars;

print "1..1\n";

my @x_values = ();     # x axis
my @y_values = ();

my $graphic;
my $picture_file = "samples/bars_4.png";
my $min_y = -5;    # max. y-values
my $max_y = 5;

my $x;
my $y;

#------------------------------------------------------------------------------------
# Start
#------------------------------------------------------------------------------------

#calculate the values
for ( my $x = -5; $x <= 5; ($x = $x+0.0005)  ) {
   push (@x_values , $x);
   if ($x != 0) {             # division by zero!
     $y = 1 / $x;

      if ($y > $max_y ){
      push(@y_values, $max_y)
     }
     elsif ( $y < $min_y) {
      push(@y_values, $min_y)
     }
     else {
       push (@y_values , $y) ;
     }
   }
   else {
     push (@y_values, 0);
   }
}

#------------------------------------------------------------------------------------
# Make it
#------------------------------------------------------------------------------------

	$graphic = Chart::Bars-> new (600,600);

	$graphic -> add_dataset ( @x_values );
	$graphic -> add_dataset ( @y_values );

	$graphic -> set ('min_val' => $min_y );
	$graphic -> set ('max_val' => $max_y);
        $graphic -> set ('min_y_ticks' => 20);
    	$graphic -> set ('skip_x_ticks' => 1000);
	$graphic -> set ('graph_border' => 18 );
	$graphic -> set ('title' => "The Integral of 1/x" );
	$graphic -> set ('grid_lines' => 'true' );
	$graphic -> set ('x_ticks' => 'vertical' );
	$graphic -> set ('legend' => 'none' );
 	$graphic -> set ('y_label' => 'f = 1 / x' );
 	$graphic -> set ('xy_plot' => 'true' );
        # use a special function to convert the y values to something special
        $graphic -> set ('f_y_tick' => \&formatter);
        $graphic -> set ('f_x_tick' => \&formatter);

	$graphic -> png ($picture_file);

	


sub formatter {
   my $y_value = shift;
   my $label = sprintf "%1.2f",$y_value;
   if ($label == '-0.00') {
     $label = '0';
   }
   
   return $label;
}
print "ok 1\n";

exit (0);