Check if there RTL characters (Arabic, Persian, Hebrew)

is_rtl.php

<?php
/**
 * Is RTL
 * Check if there RTL characters (Arabic, Persian, Hebrew)
 * this function works in fuzzy mode
 * 
 * @author	Khaled Attia <sourcecode@khal3d.com> Mahdi Ghayour <me@mghayour.ir>
 * @param	String	$string
 * @return	float betwwen 0~1, (0 for ltr and 1 for rtl)
 * @example if( is_rtl($string) > 0.5 ) { // do sth }
 */
function is_rtl( $string ) {
	$rtl_chars_pattern = '/[\x{0590}-\x{05ff}\x{0600}-\x{06ff}]/u';
	preg_match_all($rtl_chars_pattern, $string, $matches);
	$rtl_chars_count = count($matches[0]);

	$ltr_chars_pattern = '/[a-zA-Z]/';
	preg_match_all($ltr_chars_pattern, $string, $matches);
	$ltr_chars_count = count($matches[0]);

	return  $rtl_chars_count==0? 0:
		$ltr_chars_count==0? 1:
		$rtl_chars_count/($ltr_chars_count+$rtl_chars_count);
}

// Arabic Or Persian
var_dump(is_rtl('نص عربي أو فارسي')); // 1

// Hebrew
var_dump(is_rtl('חופש למען פלסטין')); // 1

// Latin
var_dump(is_rtl('Hello, World!')); // 0

// both
var_dump(is_rtl('سلام من فارسی بیشتری دارم hello')); // 0.8 (There is 80% chance of RTL string)
var_dump(is_rtl('سلام helo')); // 0.5  (both have same RTL and LTR characters, There is 50% chance of RTL string)
var_dump(is_rtl('سلام hello, i have more ltr')); // 0.19  (There is 19% chance of RTL string)

?>

Please note that you have division by zero if a number is passed as $string. Try passing '12345' for example.
You easily fix by changing line 17 to:
$ltr_chars_pattern = '/[a-zA-Z0-9_!@#$%^&*?()+-<>"]/';

@atyachin you missed some special char .. semicolon (;), colon(:)