Calling a function directly from Ionic tab - angularjs

I am trying to create my first App with Ionic. I have a few tabs as defined in app.js file.

  .state('tab.dash', {
    url: '/dash',
    views: {
      'tab-dash': {
        templateUrl: 'templates/tab-dash.html',
        controller: 'DashCtrl'
      }
    }
  })
  .state('tab.chats', {
      url: '/chats',
      views: {
        'tab-chats': {
          templateUrl: 'templates/tab-chats.html',
          controller: 'ChatsCtrl'
        }
      }
    })
  .state('tab.audioplayer', {
      url: '/audioplayer',
      views: {
        'tab-audioplayer': {
          templateUrl: 'templates/tab-audioplayer.html',
          controller: 'ExampleController'
        }
      }
    })

Here in the last tab, I do not want to open a new page like tab-audioplayer.html as currently shown. Instead, I want to call a function say MyFunction() residing in "ChatsCtrl" controller (the previous one), which does some value assignments. As I am new, I don't know how to call a function instead of opening a tab, when the tab icon is clicked. Can someone please help?

Thanks