\documentclass[12pt]{article} \pagestyle{empty} \begin{document} \begin{displaymath} P_{\rm select}^{\rm bend A}\left(\theta_{g_a,f,p}(k)\right) = {{ \left[ {{p_{\rm trial}^{\rm ideal}\left(\theta_{g_a,f,p}(k)\right)}\over{ p_{\rm trial}^{\rm arb}\left(\theta_{g_a,f,p}(k)\right)}} \exp\left[-\beta u_{\rm bend}\left(\theta_{g_a,f,p}(k)\right)\right] \right] } \over { W_{\rm bend}^{A}(j,b) }} \end{displaymath} \end{document}