In my tex file, = doesn't appear.
\RequirePackage[l2tabu]{nag}
\makeatletter
\renewcommand*\cleardoublepage{\clearpage\if@twoside
\ifodd\c@page \hbox{}\newpage\if@twocolumn\hbox{}%
\newpage\fi\fi\fi}
\makeatother
\documentclass[a4paper,12pt,openany,leqno,footinclude=true]{memoir}
\usepackage{enumitem}% http://ctan.org/pkg/enumitem
\usepackage{graphicx}
\usepackage{amssymb}
\usepackage{lineno}
\usepackage{multicol}
\usepackage{blindtext}
\RequirePackage{graphicx}
\usepackage{enumitem}
\setlist[itemize]{leftmargin=*}
%\usepackage{amsmath,fontspec}
\usepackage{subfig}
\usepackage{amsfonts}
\usepackage{algorithm,algorithmic}
\usepackage{enumitem}
\usepackage{eqparbox}
\setlist[itemize]{leftmargin=*}
\def\cftchapteraftersnum{.}
\makeatletter
\def\@copyrightspace{\relax}
\makeatother
\settrimmedsize{297mm}{210mm}{*}
\setlength{\trimtop}{0pt}
\setlength{\trimedge}{\stockwidth}
\addtolength{\trimedge}{-\paperwidth}
\settypeblocksize{634pt}{448.13pt}{*}
\setulmargins{4 cm}{*}{*}
\setlrmargins{*}{*}{1.5}
\setmarginnotes{17pt}{51pt}{\onelineskip}
\setheadfoot{\onelineskip}{2\onelineskip}
\setheaderspaces{*}{2\onelineskip}{*}
\setlrmargins{*}{*}{1}
\checkandfixthelayout
\pagestyle {plain}
\usepackage{fouriernc}
\usepackage[T1]{fontenc}
\aliaspagestyle{part}{empty}
\OnehalfSpacing
\newcommand{\clearemptydoublepage}{\newpage{\thispagestyle{empty}\cleardoublepage}}
\usepackage{import}
\usepackage{underscore}
% Add other packages needed for chapters here. For example:
\usepackage{lipsum} %Needed to create dummy text
\usepackage{amsfonts} %Calls Amer. Math. Soc. (AMS) fonts
\usepackage[centertags]{amsmath} %Writes maths centred down
\usepackage{stmaryrd} %New AMS symbols
\usepackage{amssymb} %Calls AMS symbols
\usepackage{amsthm} %Calls AMS theorem environment
\usepackage{newlfont} %Helpful package for fonts and symbols
\usepackage{layouts} %Layout diagrams
\usepackage{graphicx} %Calls figure environment
\usepackage{longtable,rotating} %Long tab environments including rotation.
\usepackage[applemac]{inputenc} %Needed to encode non-english characters
%directly for mac
\usepackage{colortbl} %Makes coloured tables
\usepackage{wasysym} %More math symbols
\usepackage{mathrsfs} %Even more math symbols
\usepackage{float} %Helps to place figures, tables, etc.
\usepackage{verbatim} %Permits pre-formated text insertion
\usepackage{upgreek } %Calls other kind of greek alphabet
\usepackage{latexsym} %Extra symbols
\usepackage[square,numbers,
sort&compress]{natbib} %Calls bibliography commands
\usepackage{url} %Supports url commands
\usepackage{etex} %eTeXÕs extended support for counters
\usepackage{fixltx2e} %Eliminates some in felicities of the
%original LaTeX kernel
\usepackage[spanish,english]{babel} %For languages characters and hyphenation
\usepackage{color} %Creates coloured text and background
\usepackage[colorlinks=true,
allcolors=black]{hyperref} %Creates hyperlinks in cross references
\usepackage{memhfixc} %Must be used on memoir document
%class after hyperref
\usepackage{enumerate} %For enumeration counter
\usepackage{footnote} %For footnotes
\usepackage{microtype} %Makes pdf look better.
\usepackage{rotfloat} %For rotating and float environments as tables,
%figures, etc.
\usepackage{alltt} %LaTeX commands are not disabled in
%verbatim-like environment
\usepackage[version=0.96]{pgf} %PGF/TikZ is a tandem of languages for producing vector graphics from a
\usepackage{tikz} %geometric/algebraic description.
\usetikzlibrary{arrows,shapes,snakes,
automata,backgrounds,
petri,topaths} %To use diverse features from tikz
%
\usepackage{mathptmx}% http://ctan.org/pkg/mathptmx
\setcounter{tocdepth}{3}
\setcounter{secnumdepth}{3}
\usepackage{tocloft}%
\newcommand{\cftchapaftersnum}{.}
\begin{document}
% -----------------------------------------------------------Pages
\let\cleardoublepage\clearpage
\input{frontmatter/title}
\end{document}
The above contains the preamble.
Consider putting in title.tex:
\[dupthresh = D\cdot[1+log(n)]\]
= does not appear.
A minimal example would be as follows:
\documentclass{article}
\usepackage{fouriernc}
\usepackage{mathptmx}
\begin{document}
$a=b$
\end{document}
\usepackage{enumitem}three times (andenumeratewhich is incompatible with that) – David Carlisle Nov 23 '15 at 15:37\input{frontmatter/title}that we don't have, and it has no examples of math which is the subject of the question? Please fix the example to be an example of the problem, preferably removing all lines that are unrelated. – David Carlisle Nov 23 '15 at 15:38=symbol appears to be present in the code you've posted, it's not possible to diagnose the situation properly, let alone propose a remedy. – Mico Nov 23 '15 at 15:40etexorfixltx2ein current latex releases andnewlfontin any latex since the 1990's. – David Carlisle Nov 23 '15 at 15:41\documentclass{article} \usepackage{fouriernc} \usepackage{mathptmx} \begin{document} $x=x$ \end{document}– cgnieder Nov 23 '15 at 15:41\usepackage[applemac]{inputenc}? (and why isgraphicxloaded three times (none of which is needed as it is loaded by rotating`)? – David Carlisle Nov 23 '15 at 15:47