4

I'm getting a missing $ in equation environment, but only when in cases environment. Of the two examples below only the equation that implements the cases environment is giving me troubles:

\documentclass[11pt,fleqn]{book} % Default font size and left-justified equations
\usepackage{pgfplots}
\pgfplotsset{compat=1.14}
\usepackage{pgfplotstable}
\usepgfplotslibrary{polar}
\usepgflibrary{shapes.geometric}
\usetikzlibrary{calc}
\usepackage{tikz}
\usepackage{booktabs}
\usepackage{fancyhdr}
\usepackage{array}
\usepackage{colortbl}
\usepackage[top=3cm,bottom=3cm,left=3.2cm,right=3.2cm,headsep=10pt,letterpaper]{geometry} % Page margins
\usepackage{xcolor} % Required for specifying colors by name
\definecolor{ocre}{RGB}{52,177,201} % Define the orange color used for highlighting throughout the book
% Font Settings
\usepackage{avant} % Use the Avantgarde font for headings
\usepackage{times} % Use the Times font for headings
\usepackage{mathptmx} % Use the Adobe Times Roman as the default text font together with math symbols from the Symbol, Chancery and Computer Modern fonts
\usepackage{microtype} % Slightly tweak font spacing for aesthetics
\usepackage[utf8]{inputenc} % Required for including letters with accents
\usepackage[T1]{fontenc} % Use 8-bit encoding that has 256 glyphs
\usepackage{amsthm}
%\usepackage{amsmath}
\usepackage{mathtools}
\DeclarePairedDelimiter\Floor\lfloor\rfloor
\DeclarePairedDelimiter\Ceil\lceil\rceil
% Bibliography
\usepackage[style=alphabetic,sorting=nyt,sortcites=true,autopunct=true,babel=hyphen,hyperref=true,abbreviate=false,backref=true,backend=biber]{biblatex}
\addbibresource{bibliography.bib} % BibTeX bibliography file
%\defbibheading{bibempty}{}

%\input{structure} % Insert the commands.tex file which contains the majority of the structure behind the template

%----------------------------------------------------------------------------------------
%   Definitions of new commands
%----------------------------------------------------------------------------------------
\def\R{\mathbb{R}}
\newcommand{\cvx}{convex}
% glossary
\begin{document}
\begin{equation}\label{Rate of exchange for Giver: ROEG}
ROE (\frac{\epsilon}{n},\iota ,b) = (1-\frac{\epsilon}{n})*\iota ^n b
\end{equation}
This is the giver's model. It will be extended to include situations where a person gives more than 
\[(1-\frac{\epsilon}{n})\].



\begin{equation}\label{Rate of exchange for Reciever: ROER}
ROE (\frac{\epsilon}{n},\iota) = 
  \begin{cases}
(1-\frac{\epsilon}{n})*\iota^n & \text{if\frac{\epsilon}{n}>1} \\
(\frac{\epsilon}{n}-1)*\iota^n & \text{if\frac{\epsilon}{n}<1} \\
  \end{cases}

\end{equation}
\end{document}
  • 5
    Remove the blank line between \end{cases} and \end{equation}. – Bernard May 12 at 14:40
  • 6
    Also, \text starts text mode, so \text{\frac{}{}} is an error because \frac requires math mode. – Torbjørn T. May 12 at 14:41
6

Some comments and suggestions. As @Bernard and @TorbjørnT. have already pointed out, you must

  • remove the blank line between \end{cases} and \end{equation}, and
  • change \text{if\frac{\epsilon}{n}>1} to \text{if }\frac{\epsilon}{n}>1, and similarly for the second case.

In addition, you should also consider replacing all three instances of * with \cdot (or omitting * entirely), typesetting the variable names using upright Roman letters, and -- this is optional -- replacing all cases of \frac{\epsilon}{n} with \epsilon/n, i.e., using inline-fraction notation.

Incidentally, there's no need to load the times package (which is obsolete anyway) since you also load mathptmx. Oh, and don't load the colortbl and xcolor packages independently; instead, run \usepackage[table]{xcolor}.

enter image description here

\documentclass[11pt,fleqn]{book}
\usepackage[vmargin=3cm,hmargin=3.2cm,headsep=10pt,letterpaper]{geometry} % Page margins
%%%\usepackage{colortbl}
%%%\usepackage{xcolor} % Required for specifying colors by name
\usepackage[table]{xcolor}
\definecolor{ocre}{RGB}{52,177,201} % Define the orange color used for highlighting throughout the book

% Font Settings
\usepackage{avant} % Use the Avantgarde font for headings
%%%%\usepackage{times} % Use the Times font for headings
\usepackage{mathptmx} % Use the Adobe Times Roman as the default text font together with math symbols from the Symbol, Chancery and Computer Modern fonts
\usepackage{microtype} % Slightly tweak font spacing for aesthetics

\usepackage[utf8]{inputenc} % Required for including letters with accents
\usepackage[T1]{fontenc} % Use 8-bit encoding that has 256 glyphs

\usepackage{amsthm}
%\usepackage{amsmath} % is loaded automatically by 'mathtools'
\usepackage{mathtools}
\DeclarePairedDelimiter\Floor\lfloor\rfloor
\DeclarePairedDelimiter\Ceil\lceil\rceil


% New user commands
\def\R{\mathbb{R}}
\newcommand{\cvx}{convex}
\newcommand\vn[1]{\mathrm{#1}}

% glossary

\begin{document}
\begin{equation}\label{Rate of exchange for Giver: ROEG}
   \vn{ROE}(\epsilon/n,\iota,b) = (1-\epsilon/n)\cdot\iota^n b
\end{equation}
This is the giver's model. It will be extended to include situations 
where a person gives more than $1-\epsilon/n$.
\begin{equation}\label{Rate of exchange for Receiver: ROER}
   \vn{ROE} (\epsilon/n,\iota) = 
   \begin{cases}
      (1-\epsilon/n)\cdot\iota^n & \text{if }\epsilon/n>1 \\
      (\epsilon/n-1)\cdot\iota^n & \text{if }\epsilon/n<1
   \end{cases}
\end{equation}
\end{document}
  • Thank you for this useful advice! – Michael Perdue May 12 at 16:13

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.