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\documentclass[a4paper,12pt]{report}
\usepackage{physics}
\usepackage{amsthm,amssymb,thmtools}
\usepackage{graphicx}
\usepackage{epstopdf}
\usepackage{caption}
\usepackage{subcaption}
\usepackage{enumerate}


\renewcommand{\thechapter}{\Roman{chapter}}
\newtheorem{theorem}{Theorem}

\declaretheoremstyle[spaceabove = 6pt, spacebelow = 6pt, headpunct={:} ,postfoothook=\noindent\hspace{-\fontdimen2\font}]{mydef}

\declaretheorem[parent=chapter,name = Def,style = mydef]{definition}
\renewcommand{\thedefinition}{\arabic{chapter}.\arabic{definition}}

\declaretheorem[numbered = no,style = mydef, name = Example]{example}
\renewcommand{\thefigure}{\arabic{figure}}

\declaretheorem[style=mydef,numbered=no]{remark}


\begin{document}
    \setcounter{chapter}{2}
    \chapter{Partial Differentiation}
    Contrary to the previous chapter, now we will discuss the continuity and differentiation of functions of several variables.
    \begin{definition}
        Let $D$ be a subset of $\mathbb{R}^2$, i.e: $$D \subseteq \mathbb{R}^2 = \{(x,y) \mid x\in \mathbb{R}, y\in\mathbb{R} \}$$
        We say that $f:D\rightarrow\mathbb{R}$ is a real-valued function of two variables, if it assigns a real number $f(x,y)\, \mathrm{to\,each}\, (x,y) \in D.$ The \emph{range} of $f$ is the set of real numbers that $f$ maps to, $R\subseteq\mathbb{R}.$
    \end{definition}
    \begin{example}
        Let $f(x,y) = \sin(x^2y) \leadsto D = {\mathbb{R}}^2\, , R\rightarrow \left[-1,-1 \right] $
    \end{example}

    \begin{example}
        Let $f(x,y) = \ln\left[1-(x^2+y^2)\right]$\\ For $D:$ $$1-(x^2+y^2)>0$$
        $$(x^2+y^2)<1$$
        $$\Rightarrow D = \{(x,y)\in\mathbb{R}^2 \mid x^2+y^2<1\} =\text{An open disc of radius}\,\, 1\,\, \text{centered at} (0,0). $$
        For R: $$ z = 1-(x^2+y^2)\in (0,1] $$ 
        $$\Rightarrow \ln(z) \in (-\infty,0]$$ 
        $$\Rightarrow R = \{x \in \mathbb{R} \mid x\le0\}$$
    \end{example}
    The figures below show the domain, range, and the function itself.
    \clearpage
    \begin{figure}
        \centering
            \begin{subfigure}[b]{0.3\textwidth}
            \includegraphics[scale=0.5]{UnitCircle_gr1.eps}
            \caption{D:\,$x^2+y^2\le1$}
        \end{subfigure}
        \,
        \begin{subfigure}[b]{0.3\textwidth}
            \includegraphics[scale=0.5]{lnz_gr1.eps}
            \caption{R:\,$\ln(z)$}
            \label{fig:tiger}
        \end{subfigure}
        \,
        \begin{subfigure}[b]{0.3\textwidth}
            \includegraphics[scale=0.5]{lnxy_gr1.eps}
            \caption{$\ln[1-(x^2+y^2)]$}
            \label{fig:mouse}
        \end{subfigure}
    \end{figure}
    \begin{definition}
        A function $f:D\rightarrow\mathbb{R}$ is called \textit{continuous at $(a,b)\in D$} if
        \begin{equation}
            \lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)=f(a,b) \tag{\ast}
        \end{equation}
        The function is called \textit{continuous} if it is continuous at every point in its domain $D$.
    \end{defintion}

    \begin{remark}
        $(\ast)$ Contains two requirements:
        \begin{enumerate}[(i)]
            \item $\lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)$ needs to exist.
            \item $\lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)$ has to be equal to $f(a,b)
        \end{enumerate}
    \end{remark}

\end{document}

enter image description here

Why is the second item in the list being created without an indent? How do I fix this?

  • Please always post a complete document that generates the problem, it is hard to debug fragments, especially fragments using environments not defined by default. – David Carlisle Feb 24 '17 at 7:45
  • @DavidCarlisle My mistake, I have updated the original post to the full tex document – Hushus46 Feb 24 '17 at 7:46
  • The problem does not exists for me, the indentation is the same for the two items. Please post a minimal example, yours isn't minimal at all and won't compile correctly since some delimiters are missing, defintion insted of definition, etc. – mvienney Feb 24 '17 at 8:03
  • Wow, it seems the error is removed when the typo is fixed. A silly error by me, apologies for the simple solution. Thanks for the help – Hushus46 Feb 24 '17 at 8:06
2

There is a missing $ at the end of the second \item. It should be ... to $f(a,b)$. Then it will be correct!

enter image description here

However, there are some other problems. marked by %%!!:

\begin{definition}
A function $f:D\rightarrow\mathbb{R}$ is called \textit{continuous at $(a,b)\in D$} if
\begin{equation}
    \lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)=f(a,b) \tag{$\ast$}%%!!!
\end{equation}
The function is called \textit{continuous} if it is continuous at every point in 
its domain $D$.
\end{definition}%%!! Was a typo here, missing i

\begin{remark}
$(\ast)$ Contains two requirements:
    \begin{enumerate}[(i)]
    \item $\lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)$ needs to exist.
    \item $\lim\limits_{(x,y)\rightarrow (a,b)} f(x,y)$ has to be equal to $f(a,b)$
    \end{enumerate}
\end{remark}

\end{document}

And, by the way, use \[...\] instead of $$...$$

  • One small question: On line 72 of my code where I have an \equation{end} within the definition of continuity, I'm getting multiple errors from "physics.sty" saying things like "Missing $ inserted" & "Extra }" & "Missing } inserted". However, the equation shows up properly in the pdf and nothing goes wrong in the actual output. I checked and I don't seem to be missing any delimiters, something seems to be clashing with the displaymath style of equation and something in this physics package.. but I'm not sure what it is – Hushus46 Feb 24 '17 at 8:14
  • see edited answer ... – user2478 Feb 24 '17 at 8:42
  • Thank you, that makes a lot of sense and solves all the issues. Okay I will use the square bracketing display math style from now on, but is there a specific reason? (just asking as I'm quite new to Latex so I'm not sure of all the intricacies) – Hushus46 Feb 24 '17 at 8:46
  • In some cases there will be a wrong spacing – user2478 Feb 24 '17 at 8:50

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