\documentclass[screen, aspectratio=43]{beamer}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}

% Use the NTNU-temaet for beamer 
% \usetheme[style=ntnu|simple|vertical|horizontal, language=bm|nn|en]{ntnu2015}
\usetheme[style=ntnu,language=en]{ntnu2015}
 
\title[Short title]{The full and long title of the presentation}
\subtitle{Subtitle if you want}
\author[O. Nordmann]{Ola Nordmann}
\institute[NTNU]{Department of LaTeX-ical sciences, NTNU}
\date{1 January 1970}
%\date{} % To have an empty date


\begin{document}

% Special title page command to get a different background
\ntnutitlepage

\begin{frame}
  \frametitle{Main theorem}
  \begin{theorem}
    LaTeX makes things easier.
  \end{theorem}
\end{frame}

\end{document}