I use PHP 4.0.5 and Apache 1.3.12

My script :
<?
$pdf=pdf_new();
$im = ImageCreate(100, 100);
$col = ImageColorAllocate($im, 80, 45, 190);
ImageFill($im, 10, 10, $col);
$pim = PDF_open_memory_image($pdf, $im);
ImageDestroy($im);
PDF_place_image($pdf, $pim, 100, 100, 1);
PDF_close_image($pdf, $pim);
?>

The server's answer :

Fatal error: Call to undefined function: pdf_open_memory_image() in c:\web\essaipdfnew.php on line 6