Math & Science ⇒ The best way to emphasize equations ?

[Cham]

I need to emphasize some mid-paragraph equations. Of course, I'm using the \begin{equation} ... \end{equation} environment, and I tried the \boxed{ } option. However, the box is often too small around the equation, which doesn't "breathe well" inside the box. I tried adding some invisible characters inside the box, like \phantom{\Big|}, so the box becomes larger, but the results aren't very satisfying.

What do you suggest, to make a nice looking emphasized equation ?

[localghost]

The empheq package from the mh bundle is your friend.


Thorsten

[Cham]

I'm yet unable to make it to work. For example, I used this code :

Code: Select all

\begin{empheq}[boxtype=\fbox]
	\begin{equation}
		\label{hamiltonian}
			H(q, p) = \tensor{\dot q}{^i} \hspace{1pt} \tensor{p}{_i} - L.
	\end{equation}
	\end{empheq}

I'm getting several error messages when I try to compile it. Of course, I declared the \usepackage{empheq} in my preamble.

[localghost]

Please get used to always providing a minimal example that is compilable as is. It is essential for instant help. Especially in cases where the problem is much more complicated.

You didn't use the »empheq« environment correctly. This environment needs a certain syntax as described in the package manual.

Code: Select all

\documentclass[11pt,a4paper]{report}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}   % loads »amsmath«
\usepackage{empheq}
\usepackage{tensor}

\begin{document}
  \begin{empheq}[box=\fbox]{equation}\label{eqn:hamiltonian}
    H(q,p) = \tensor{\dot{q}}{^i}\,\tensor{p}{_i}-L
  \end{empheq}
\end{document}

[Cham]

Haa ! Ok, now it's working. Wasn't obvious !

EDIT : Wow ! Now it's awesome . This is exactly what I need !

Again, thanks A LOT for all of your precious help !

[Cham]

I'm back on this topic with a desire !

Currently, my emphasized equations are all working great, but I would like to add a simple black line all around the gray box (no white space), or even a double-frame. Here's a compilable example of a gray box around an equation :

Code: Select all

\documentclass[11pt,a4paper]{report}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\usepackage{empheq}
\usepackage{tensor}
\usepackage[dvipsnames,table]{xcolor}
\definecolor{someGray}{RGB}{230,230,230}

\begin{document}
  \begin{empheq}[box={\setlength{\fboxsep}{10pt}\colorbox{someGray}}]{equation}
    H(q,p) = \tensor{\dot{q}}{^i}\,\tensor{p}{_i}-L
  \end{empheq}
\end{document}

How should I modify that example to add a black line around the gray box ?

What about a black double-frame around the gray box, for the most extremely important equations ?

The empheq package documentation isn't obvious about this !

[Cham]

I'VE FOUND IT !

Geez, I had to experiment a lot before finding this one !

Here's a compilable code to emphasize equations with a gray box, and a gray box with a red frame. The colors can be edited very easily.

Code: Select all

\documentclass[11pt,a4paper]{report}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage{mathtools}
\usepackage{empheq}
\usepackage{tensor}
\usepackage[dvipsnames,table]{xcolor}
\definecolor{medGray}{RGB}{230,230,230}

\newenvironment{important}[2][]{
	\setkeys{EmphEqEnv}{#2}
	\setkeys{EmphEqOpt}{box={\setlength{\fboxsep}{10pt}\colorbox{medGray}},#1}
	\EmphEqMainEnv}
{\endEmphEqMainEnv}

\newenvironment{tres important}[2][]{
	\setkeys{EmphEqEnv}{#2}
	\setkeys{EmphEqOpt}{box={\setlength{\fboxsep}{10pt}\fcolorbox{red}{medGray}},#1}
	\EmphEqMainEnv}
{\endEmphEqMainEnv}

\begin{document}

  \begin{tres important}{equation}
	H(q,p) = \tensor{\dot{q}}{^i}\,\tensor{p}{_i}-L
  \end{tres important}

  \begin{important}{equation}
	H(q,p) = \tensor{\dot{q}}{^i}\,\tensor{p}{_i}-L
  \end{important}

\end{document}

Here's a preview :

box.jpg (9.84 KiB) Viewed 12953 times

[Stefan Kottwitz]

Nice solution, thanks for posting the complete example with screenshot!

Stefan