7

I already had issues (described here: amsmath package error using SIAM LaTeX template files) with the newest version of SIAM LaTeX template from http://www.siam.org/journals/auth-info.php

For now, I would like to clarify why the position of QED symbol in the proof environment depends on the equation environment type. Using example from manual with \begin{displaymath}\end{displaymath}:

\begin{corollary}
  Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
  has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
  Let $a$ and $b$ be two distinct roots of $f$.
  By \cref{thm:mvt}, there exists a number $c$ such that
  \begin{displaymath}
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
  \end{displaymath}
\end{proof}

puts QED symbol at the right position (end of the equation). enter image description here

However, using $$ $$ QED symbol is completely absent from the proof environment:

\begin{corollary}
    Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
    has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
    Let $a$ and $b$ be two distinct roots of $f$.
    By \cref{thm:mvt}, there exists a number $c$ such that
    $$
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
    $$
\end{proof}

enter image description here

Finally, using \begin{equation*}\end{equation*} puts QED symbol in a wrong position, i.e., above the equation.

\begin{corollary}
  Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
  has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
  Let $a$ and $b$ be two distinct roots of $f$.
  By \cref{thm:mvt}, there exists a number $c$ such that
  \begin{equation*}
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
  \end{equation*}
\end{proof}

enter image description here

My questions are following:

  1. Is this behavior typical for any proof environment containing math equations and adding the QED symbol at the end of it; or this another 'bug' in SIAM template file?

  2. What is the correct way to type in proof environment math equations? Previously I have used most often \begin{equation*}\end{equation*}, but here it produces the wrong behavior.

  • 1
    You should never use $$ in LaTeX and this rules out one of your problems, see Why is \[ … \] preferable to $$?. Can you please show a minimal example of code from \documentclass to \end{document}? – egreg Sep 12 '16 at 12:46
6

First of all, never ever use $$...$$ in LaTeX: you have discovered another reason why, but please have a look at Why is \[ ... \] preferable to $$ ... $$?

Second, it's another feature of ntheorem with the thmmarks option, that modifies some environments but not all in order to provide automatic placement of the tombstone.

In particular equation* doesn't get redefined, so it's not in line with the automatic placement. You can make it compatible by redefining it.

\documentclass[
  %review
]{siamart0516}
\usepackage{amsmath}

\usepackage{etoolbox}
% fix for https://tex.stackexchange.com/questions/328946
\patchcmd{\SetTagPlusEndMark}{$}{}{}{}
\patchcmd{\SetTagPlusEndMark}{$}{}{}{}

% fix for the QED in equation*    
\renewenvironment{equation*}{\[}{\]\ignorespacesafterend}

\begin{document}
\begin{equation}
\bar{x} = x + y
\tag{$\bar{x}$}
\label{eq:x}
\end{equation}

\begin{corollary}
  Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
  has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
  Let $a$ and $b$ be two distinct roots of $f$.
  By \cref{thm:mvt}, there exists a number $c$ such that
  \begin{displaymath}
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
  \end{displaymath}
\end{proof}

\begin{corollary}
  Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
  has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
  Let $a$ and $b$ be two distinct roots of $f$.
  By \cref{thm:mvt}, there exists a number $c$ such that
  \begin{equation*}
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
  \end{equation*}
\end{proof}

\begin{corollary}
  Let $f(x)$ be continuous and differentiable everywhere. If $f(x)$
  has at least two roots, then $f’(x)$ must have at least one root.
\end{corollary}
\begin{proof}
  Let $a$ and $b$ be two distinct roots of $f$.
  By \cref{thm:mvt}, there exists a number $c$ such that
  \begin{equation}
    f’(c) = \frac{f(b)-f(a)}{b-a} = \frac{0-0}{b-a} = 0.
  \end{equation}
\end{proof}

\end{document}

However, equation will not push the QED in the same position as equation* (I deem wrong the placement in equation*, but apparently this pleases the author of ntheorem).

enter image description here

  • I have found a slight misbehaviour if the review option of siamart171218 is used. I fixed it with \renewenvironment{equation*}{\[}{\]\ignorespacesafterend}. – gerw Sep 6 '18 at 8:19
  • @gerw That's a very good suggestion – egreg Sep 6 '18 at 8:29

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.