# center align equation in ‎\documentclass[11pt,twoside,fleqn]{book}‎

I used the ‎\documentclass[11pt,twoside,fleqn]{book}‎ for set formulas left, but I want to put formulas to center in some cases like original type without [fleqn]. What command do I use? %%%%%%%%%%%%%% ‎

\documentclass[11pt,twoside,fleqn]{book}‎‎
‎‎\usepackage{amsmath,amsfonts,amssymb,amsthm}‎
\begin{document}
‎\begin{align*}‎‎%This is in left
‎y=f(x)
‎\end{align*}‎‎
\begin{align*}‎‎%This should be at the center
\centering
‎y=g(x)
‎\end{align*}‎
\end{document}


\begin{ceqn}\begin{align*} ‎y=g(x) ‎\end{align*}‎\end{ceqn}