How to load a controller from another controller in codeigniter?

I want to load a controller from a function in another controller because the library I integrated to my project I don't want to load it to the controller because I want to keep it clean and related.

I tried using modules but I still had to put controller in the url like

http://example.com/maincontroller/function
http://example.com/othercontroller/function

I have default controller so I can load http://example.com/function so how could I access the controller from a function from main so I don't have to put the controller in the url.

I'm still willing to use HMVC if I can load the controller function from the main controller function.

you cannot call a controller method from another controller directly

my solution is to use inheritances and extend your controller from the library controller

class Controller1 extends CI_Controller {

    public function index() {
        // some codes here
    }

    public function methodA(){
        // code here
    }
}

in your controller we call it Mycontoller it will extends Controller1

include_once (dirname(__FILE__) . "/controller1.php");

class Mycontroller extends Controller1 {

    public function __construct() {
        parent::__construct();
    }

    public function methodB(){
        // codes....
    }
}

and you can call methodA from mycontroller

http://example.com/mycontroller/methodA

http://example.com/mycontroller/methodB

this solution worked for me