Dat kernel generator

<!doctype html>
<html>
<head>
    <title>Fuck you Tobba</title>
    <!-- seriously get fucked -->
</head>
<body>
<?php
/**
 * gaussianKernel.php
 * Created by William Schaller
 * Date: 8/20/2014
 * Time: 9:43 PM
 */

function generateKernel($size)
{
    $amplitude = 1; // This should be 1 probably...
    $center = 0;
    $spread = $size / 5;
    $max = floor($size / 2);
    $min = -1 * $max;

    $kernel = array();
    // Allocate array
    for ($i = $min; $i <= $max; $i++) {
        $kernel[$i] = array();
    }

    for ($i = $min; $i <= $max; $i++) {
        for ($j = $min; $j <= $max; $j++) {
            $kernel[$j][$i] = number_format(
                (float)$amplitude * exp(
                    -1 * (
                        pow((float)$j - (float)$center, 2) / (2 * pow((float)$spread, 2))
                        + pow((float)$i - (float)$center, 2) / (2 * pow((float)$spread, 2))
                    )
                ),
                3);
        }
    }

    return $kernel;
}

function kernelToTable($kernel) {
    $html = "<table>";
    $head = array_keys(reset($kernel));
    $html .= "<thead><tr>";
    foreach($head as $cell) {
        $html .= "<td>$cell</td>";
    }
    $html .= "</tr></thead>";
    foreach($kernel as $row) {
        $html .= "<tr>";
        foreach($row as $cell) {
            $html .= "<td>$cell</td>";
        }
        $html .= "</tr>";
    }

    $html .= "</table>";
    echo $html;
}

$kernels = array();

for($i = 3; $i < 20; $i += 2) {
    $kernels[$i] = generateKernel($i);
}

array_map("kernelToTable", $kernels);
?>
</body>
</html>