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#!/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);
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