regexps in PHP

/*
 *
 *  Searchs de string for latex code (between $$) and returns link with the corresponding image if found
 *
 */

    function replaceLatex($text){

        $match = preg_match_all('(\$[^\$]*\$)',$text,$latexTextArray);
        //if there isnt latex in the text
        if ($match==0) return $text;


        $replacedText=$text;
        foreach ($latexTextArray[0] as &$latexText){
            //Remove the $ signs
            $result = substr($latexText,1);
            $result = substr($result,0,-1);

            //We replace the text for the latex img
            $replacedText = str_replace($latexText, "<img src=\"http://latex.codecogs.com/gif.latex?".$result."\" border=\"0\"/> ", $replacedText);

        }
        return $replacedText;
    }