I have error
! Missing } inserted. } l.9 { -1+2/[1+3\exp(-2|J|/k_BT)],& $T
MWE
\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{eqnarray} \label{eq:Cd}
\tilde C(T)=
\begin{cases}
{ -1+2/[1+3\exp(-2|J|/k_BT)],& $T<T_e$;\cr\cr 0,& $T\ge T_e$.\cr}
\end{cases}
\end{eqnarray}
\end{document}
When i comment \usepackage{amsmath}
there is no error. I can't understand how to fix it, without \usepackage{amsmath}
commenting.
amsmath
.