Well the last reply in that node DID get the axis to shift to 0.

#!/usr/bin/perl
use warnings;
use strict;
use GD::Graph::lines;

# See:  http://perlmonks.org?node_id=629955

use constant PI => 4 * atan2(1,1);
print STDERR "Processing sample55\n";
my @x = map {$_ * 3 * PI/100} (0 .. 100);
my @y = map sin, @x;
my @z = map cos, @x;
my @data = (\@x,\@y,\@z);

my $my_graph = new GD::Graph::lines(400,400);

$my_graph->set(
x_label => 'Angle (Radians)',
y_label => 'Trig Function Value',
x_tick_number => 'auto',
y_tick_number => 'auto',
title => 'Sine and Cosine',
line_width => 1,
x_label_position => 1/2,
r_margin => 15,
transparent => 0,
);
$my_graph->set_legend('Thanks to Scott Prahl');
my $gd = $my_graph->plot(\@data);

open (IMG, ">$0.png") or die $!;
binmode IMG;
print IMG $gd->png;
close IMG;
[download]

However, I tried to put your data into the exact same script, and it wouldn't go to 0...... I think GD::Graph::lines is buggy about this. I tried mapping your data, tried changing your text axis marks to numeric... (0,1,2,3).... and it still wouldn't shift. Very aggravating.