Ok, I finally got it now, understanding transform:
function compass(){
$angle = array(0,45,90,135,180,225,270,315);
for ($i = 0; $i <= 7; $i++) {
$a = $angle[$i];
$Ox1 = 50;
$Oy1 = 50;
$rad = 40;
$x = 50 + round($rad*cos(deg2rad($a)));
$y = 50 - round($rad*sin(deg2rad($a)));
//echo 'x= '.$x.' | y= '.$y.'<= for angle '.$a.'<br>';
$html = '<line x1="'.$Ox1.'" y1="'.$Oy1.'" x2="'.$x.'" y2="'.$y.'" style="stroke:red;stroke-width:2"/>';
$html = $html++;
echo $html;
}
}
?>
<svg id="svgelem" height="100" xmlns="http://www.w3.org/2000/svg">
<