AngularJS. How to call controller function from outside of controller component

How I can call function defined under controller from any place of web page (outside of controller component)?

It works perfectly when I press “get” button. But I need to call it from outside of div controller. The logic is: by default my div is hidden. Somewhere in navigation menu I press a button and it should show() my div and execute “get” function. How I can achieve this?

My web page is:

<div ng-controller="MyController">
  <input type="text" ng-model="data.firstname" required>
  <input type="text" ng-model="data.lastname" required>

  <form ng-submit="update()"><input type="submit" value="update"></form>
  <form ng-submit="get()"><input type="submit" value="get"></form>
</div>

My js:

   function MyController($scope) {
      // default data and structure
      $scope.data = {
        "firstname" : "Nicolas",
        "lastname" : "Cage"
      };

      $scope.get = function() {
        $.ajax({
           url: "/php/get_data.php?",
           type: "POST",
           timeout: 10000, // 10 seconds for getting result, otherwise error.
           error:function() { alert("Temporary error. Please try again...");},
           complete: function(){ $.unblockUI();},
           beforeSend: function(){ $.blockUI()},
           success: function(data){
            json_answer = eval('(' + data + ')');
            if (json_answer){
                $scope.$apply(function () {
                  $scope.data = json_answer;
            });
            }
        }
    });
  };

  $scope.update = function() {
    $.ajax({
        url: "/php/update_data.php?",
        type: "POST",
        data: $scope.data,
        timeout: 10000, // 10 seconds for getting result, otherwise error.
        error:function() { alert("Temporary error. Please try again...");},
        complete: function(){ $.unblockUI();},
        beforeSend: function(){ $.blockUI()},
        success: function(data){ }
      });
    };
   }