Gaussian Chart with jpgraph - php

Question

I´m trying to graph a gaussian chart in php. I found the jpgraph library, but I don´t know how to use the $x, $y data. Please somebody who knows how to declare the axis. Thanks. This is my code:
while ($row = pg_fetch_assoc($sql))
{
$ydata = array();
$xdata = array();
$ydata[] = abs(($row['grade']-$miu)/$sigma);
$xdata[] = 0;
for ($i = 0; $i <= 60; $i+=10) // put z value
{
$xdata[] = 0 + $i;
$ydata[] = 0 + $i;
}
$graph = new Graph(600,400,"auto");
$graph->SetScale("linlin");
$lplot = new LinePlot($ydata,$xdata);
$lplot->SetColor("blue");
$lplot->SetWeight(2);
$graph->Add($lplot);
// Add data to X coordinate
$graph->xaxis->SetTickLabels($xdata);
// Display the graph
$graph->Stroke();
}

Answer 1

I already resolved it.
while ($row = pg_fetch_assoc($sql))
{
$z[$i] = ($row['grade'] - $miu)/$sigma; // $z => arreglo con notas normalizadas
$ordenada[$i] = (1/($sigma*sqrt(pi())))*(exp(-0.5*(($row['grade']-$miu)*($row['grade'] - 57))/(12*12)));
$i++;
}
//rest of code
$p1 = new LinePlot($ordenada);
$graph->Add($p1);