call to undefined function cmpfx().. what does that mean?

if (isset($_SESSION["admin"])) redirect("home.php");

if (!empty($_POST)) {
//$rs = getconfigvar("admin_username,admin_password");
$sql="select * from user_master where 'user_name'='admin'";
// $sql="select * from user_master where active=1 and user_type in (1,2) and user_name='".pdbfx("username")."'";
$cmd = mysql_query($sql);
$rs = mysql_fetch_array($cmd);
/*echo $rs["password"]."-".pdbfx("password");
echo cmpfx($rs["password"], pdbfx("password"));
echo $sql;
die;*/
if (cmpfx($rs["user_name"], $_POST["username"]) && cmpfx($rs["password"], md5($_POST["password"]))) {
$_SESSION["admin"] = $_POST["username"];
$_SESSION["user_type"] =$rs["user_type"];
$_SESSION["user_id"] =$rs["user_id"];

redirect("home.php");
}
else {
setErr("<div class='response-msg error ui-corner-all'> <span>Invalid Username or Password </span></div>");
redirect("index.php");
}
}

Greetings,

It means that on this line;
you're calling the function 'cmpfx' which has not been defined. So you would need to define the function like so;
You'd replace the '// function code in here' with code to work on the 2 passed values and then return a result.