\documentclass[12pt]{article} \pagestyle{empty} \begin{document} \begin{displaymath} p_{\rm trial}^{\rm ideal}(\phi_{\rm g_a,f,p,e}) = {{1}\over{2 \pi}} \end{displaymath} \end{document}
\documentclass[12pt]{article} \pagestyle{empty} \begin{document} \begin{displaymath} p_{\rm trial}^{\rm ideal}(\phi_{\rm g_a,f,p,e}) = {{1}\over{2 \pi}} \end{displaymath} \end{document}