loan end date

function loan_close_date($outstanding, $roi, $emi, $update_date)
{
    $nop = 0; // number of payments

    while($outstanding>$emi)
    {
        $interest = $outstanding*$roi/1200;
        $outstanding = $outstanding + $interest - $emi;
        $nop = $nop + 1;
    }

    $days = ceil(30* $outstanding / $emi);
    $ud = date('Y-m-d', strtotime("+".$nop." months", strtotime($update_date)));
    $ud = date('Y-m-d', strtotime("+".$days." days", strtotime($ud)));

    return $ud;
}