\documentclass{article} 
%\usepackage{url}
%\usepackage{fancyvrb}
%\usepackage{setspace}\doublespacing
%\usepackage{graphicx} 
%\usepackage{amssymb}
%\usepackage{makeidx}
\usepackage{breqn}
%\usepackage{amssymb}
\usepackage{xepersian}
\settextfont[Scale=1]{XB Zar}
\setlatintextfont[Scale=1]{Times New Roman}
\setdigitfont{XB Zar}
\setpookfont{XB Kayhan Pook}
\setsayehfont{XB Kayhan Sayeh}
\defpersianfont\lotoos[Scale=1.2]{XB Roya}
\defpersianfont\elmi[Scale=1.2]{XB Roya} 
\def\nazok{\normalfont\normalsize}
\let\iranic\it
\let\siah\bf
\let\khabide\sl
\def\siahir{\siah\iranic} 
\def\siahkh{\siah\khabide}
\let\tookhali\pookfamily
\let\sayedar\sayehfamily
\let\farsi\Persian
\let\english\Latin 
\let\farmbox\mbox
\newcommand{\ftxepmatrix}[1]{\begin{pmatrix}#1\end{pmatrix}}
\newcommand{\ftxematrix}[1]{\begin{matrix}#1\end{matrix}} 
\def\FarsiTeX{\lr{FarsiTeX}}
\def\فارسی‌تک{\rl{فارسی‌‌تک}}
\def\InE{\begingroup\beginL\latinfont}
\def\EnE{\endL\endgroup} 
\def\InF{\begingroup\beginR\persianfont}
\def\EnF{\endR\endgroup}
\newcommand{\IE}[1]{\lr{#1}}
\newcommand{\IP}[1]{\rl{#1}} 
\newcommand{\IF}[1]{\rl{#1}}
\def\persiandash{\rl{-}} 
\def\DeclareRobustBiCommand#1#2#3#4{\DeclareRobustCommand#1{\if@rl{}#4\else{}#3\fi}\let#2=#1} 
\catcode`\﷼=3
\catcode`‌=11
\newcommand\dotsectionseparator{\SepMark{.}}
\newcommand\dashsectionseparator{\SepMark{-}}
\title{{\huge\sayedar اشکال در شکستن خودکار فرمول‌ها}}      .
\author{{\large آرش فهیم}}


\input{symbols}

\begin{document}


\maketitle


\begin{dmath*}
dX_t=\theta_{t,1}dS_{t,1}+\cdots+\theta_{t,d}dS_{t,d}+(X_t-\theta_{t,1}S_{t,1}-\cdots-\theta_{t,d}dS_{t,d})rdt.
\end{dmath*}

\end{document}