fixed for $$

app/controllers/home.controller.js

 
             $scope.formatText = function(text)
             {
-                text = text.replace(/\$([^\$]+)\$/g, function($1, $2)
+                text = text.replace(/\$\$([^\$]+)\$\$/g, function($1, $2)
+                {
+                    return "\\(" + $2 + "\\)";
+                }).replace(/\$([^\$]+)\$/g, function($1, $2)
                 {
                     return "\\(" + $2 + "\\)";
                 }).replace(/\\medskip/g, "")