[Tex/LaTex] Making a box around an equation

alignboxes

I have a summary of equations which is written in an align environment. I want to make a box around it but don't know how to do this efficiently. Here is a MWE

\documentclass{article}
\usepackage[fleqn]{amsmath}

\setlength\mathindent{1cm}
\linespread{1.3}

\begin{document}

\textbf{\Large Solution.} Here is a summary of what we obtained in class for the case of periodic distribution of eigen-strain
\begin{align*}
&\text{Given the system of PDEs} \\
&C_{ijkl}u_{k,lj} = C_{ijkl} \varepsilon^*_{kl,j} \\
&\text{with a periodic distribution of eigen-strain} \\
&\varepsilon^*_{kl}(\mathbf{x},\boldsymbol{\xi})=\bar{\varepsilon}^*_{kl}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\text{the general solution can be obtained as} \\
&K_{ik} = C_{ijkl}\xi_l\xi_j \\
&D(\boldsymbol{\xi}) = \epsilon_{mnl} K_{m1} K_{n2} K_{l3} \\
&N_{ij}(\boldsymbol{\xi}) = \frac{1}{2} \epsilon_{ikl}\epsilon_{jmn} K_{km} K_{ln} \\
&u_i(\mathbf{x},\boldsymbol{\xi}) = -\mathrm{i}\,C_{jlmn} \bar{\varepsilon}^*_{mn} \xi_l N_{ij}(\boldsymbol{\xi}) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\varepsilon_{ij}(\mathbf{x},\boldsymbol{\xi}) = C_{klmn} \bar{\varepsilon}^*_{mn} \xi_l ( \xi_j N_{ik}(\boldsymbol{\xi}) + \xi_i N_{jk}(\boldsymbol{\xi})) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\sigma_{ij}(\mathbf{x},\boldsymbol{\xi}) = C_{ijkl} ( C_{pqmn} \bar{\varepsilon}^*_{mn} \xi_q \xi_l N_{kp}(\boldsymbol{\xi}) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x})-\varepsilon^*_{kl}(\mathbf{x}))
\end{align*}

\end{document}

Best Answer

I see you use amsmath, which has a nice \boxed command. The only catch is you should use aligned instead of align* inside it:

\documentclass{article}
\usepackage[fleqn]{amsmath}
\thispagestyle{empty}
\setlength\mathindent{1cm}
\linespread{1.3}

\begin{document}

\textbf{\Large Solution.} Here is a summary of what we obtained in class for the case of periodic distribution of eigen-strain

\boxed{\begin{aligned}
&\text{Given the system of PDEs} \\
&C_{ijkl}u_{k,lj} = C_{ijkl} \varepsilon^*_{kl,j} \\
&\text{with a periodic distribution of eigen-strain} \\
&\varepsilon^*_{kl}(\mathbf{x},\boldsymbol{\xi})=\bar{\varepsilon}^*_{kl}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\text{the general solution can be obtained as} \\
&K_{ik} = C_{ijkl}\xi_l\xi_j \\
&D(\boldsymbol{\xi}) = \epsilon_{mnl} K_{m1} K_{n2} K_{l3} \\
&N_{ij}(\boldsymbol{\xi}) = \frac{1}{2} \epsilon_{ikl}\epsilon_{jmn} K_{km} K_{ln} \\
&u_i(\mathbf{x},\boldsymbol{\xi}) = -\mathrm{i}\,C_{jlmn} \bar{\varepsilon}^*_{mn} \xi_l N_{ij}(\boldsymbol{\xi}) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\varepsilon_{ij}(\mathbf{x},\boldsymbol{\xi}) = C_{klmn} \bar{\varepsilon}^*_{mn} \xi_l ( \xi_j N_{ik}(\boldsymbol{\xi}) + \xi_i N_{jk}(\boldsymbol{\xi})) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x}) \\
&\sigma_{ij}(\mathbf{x},\boldsymbol{\xi}) = C_{ijkl} ( C_{pqmn} \bar{\varepsilon}^*_{mn} \xi_q \xi_l N_{kp}(\boldsymbol{\xi}) D^{-1}(\boldsymbol{\xi})\exp(\mathrm{i}\,\boldsymbol{\xi}\cdot\mathbf{x})-\varepsilon^*_{kl}(\mathbf{x}))
\end{aligned}}

\end{document}

Solution 0

Of course, there is the solution that brought you to this: Just use one node that gets drawn and filled:

\NewDocumentCommand{\tikzmarksolo}{O{} O{} m}{% needs hf-tikz (uses same style, no beamer)
    \tikz[remember picture]
    \node[line width=1pt,rectangle,fill=\fcol,#1,draw=\bcol, anchor=base]
    (pic cs:#2) {$\displaystyle #3$};%  #2 shouldn’t be optional,
                                     %  either drop (pic cs:#2) if #2 is empty
                                     %  or make it mandatory
}

Solution 1 and 2

Solution 1 and 2 are very similar, they only differ on how they catch the math content:

uses an optional last argument that is delimited by { }.

If there is a last argument (#5 in the code) it is used to determine its height and depth. Those are added to the rectangle.
uses the ending \tikzmarkend to find the math content. The same procedure follows always (height, depth, …). This will break heavily if you nest hf-tikzs.

Which brings me to the advantages of the „uselessness“ of hf-tikz: It works across & alignments and line-breaks of the amsmath environments, and it could even be nested.

Solution 3

A compromise: Solution works like the original but instead of having to specify the amount of height and depth, it determines those from math content given as optional arguments.

Codes/Outputs

Code 1 (optional `{ }` argument)

\documentclass{article}

\usepackage{hf-tikz}
\newsavebox\qrrTikzmarkBox
\RenewDocumentCommand{\tikzmarkin}{O{} m D(){0.1,-0.18} D(){-0.1,0.35} G{}}{%
\if\relax\detokenize{#5}\relax
    \dp\qrrTikzmarkBox=0pt\relax
    \ht\qrrTikzmarkBox=0pt\relax
\else
    \sbox\qrrTikzmarkBox{$\displaystyle#5$}
\fi
\tikz[remember picture,overlay]
\draw[line width=1pt,rectangle,fill=\fcol,#1,draw=\bcol]
(pic cs:#2) ++([yshift=-\the\dp\qrrTikzmarkBox]#3) rectangle ([yshift=\the\ht\qrrTikzmarkBox]#4) node [anchor=text] (#2) {}
;
#5
}
\begin{document}

\[\tikzmarkin{a}x + y = 400\tikzmarkend{a}\]

\[
\tikzmarkin{z2}{
\int_{
    E - \frac{\Delta}{2} \le H \le E + \frac{\Delta}{2} \le H
    }
     d^{3N} x d^{3N} p
    =
    \left( \frac{2 \pi \Delta}{\omega} \right)^{3N}}
\tikzmarkend{z2}
\]
\end{document}

Output 1

enter image description here

Code 2 (catches anything until `\tikzmarkend`)

\documentclass{article}

\usepackage{hf-tikz}
\newsavebox\qrrTikzmarkBox
\RenewDocumentCommand{\tikzmarkin}{O{} m D(){0.1,-0.15} D(){-0.1,0.18} u{\tikzmarkend}}{%
\ifx\\#5\\
    \dp\qrrTikzmarkBox=0pt\relax
    \ht\qrrTikzmarkBox=0pt\relax
\else
    \sbox\qrrTikzmarkBox{$\displaystyle#5$}
\fi
\tikz[remember picture,overlay]
\draw[line width=1pt,rectangle,fill=\fcol,#1,draw=\bcol]
(pic cs:#2) ++([yshift=-\the\dp\qrrTikzmarkBox]#3) rectangle ([yshift=\the\ht\qrrTikzmarkBox]#4) node [anchor=text] (#2) {}
;
#5
\tikzmarkend
}
\begin{document}

\[\tikzmarkin{a}x + y = 400\tikzmarkend{a}\]

\[
\tikzmarkin{z2}
\int_{
    E - \frac{\Delta}{2} \le H \le E + \frac{\Delta}{2} \le H
    }
     d^{3N} x d^{3N} p
    =
    \left( \frac{2 \pi \Delta}{\omega} \right)^{3N}
\tikzmarkend{z2}
\]
\end{document}

Output 2

enter image description here

Code 3 (optional argument with math content)

\documentclass{article}
\usepackage{hf-tikz}
\newsavebox\qrrTikzmarkBoxA
\newsavebox\qrrTikzmarkBoxB
\RenewDocumentCommand{\tikzmarkin}{O{} m O{} O{0}}{%
\if\relax\detokenize{#3}\relax
    \dp\qrrTikzmarkBoxA=0pt\relax
\else
    \sbox\qrrTikzmarkBoxA{$\displaystyle#3$}
\fi
\if\relax\detokenize{#4}\relax
    \ht\qrrTikzmarkBoxB=0pt\relax
\else
    \sbox\qrrTikzmarkBoxB{$\displaystyle#4$}
\fi
\tikz[remember picture,overlay]
\draw[line width=1pt,rectangle,fill=\fcol,#1,draw=\bcol]
(pic cs:#2) ++([yshift=-\the\dp\qrrTikzmarkBoxA] 0.1,-0.18) rectangle ([yshift=\the\ht\qrrTikzmarkBoxB] -0.1,0.15) node [anchor=text] (#2) {}
;
}
\begin{document}
\[\tikzmarkin{a}x + y = 400\tikzmarkend{a}\]

\[
\tikzmarkin{z2}[\int_{\frac{\Delta}{2}}][\left( \frac{2 \pi \Delta}{\omega} \right)^{3N}]
\int_{
    E - \frac{\Delta}{2} \le H \le E + \frac{\Delta}{2} \le H
    }
     d^{3N} x d^{3N} p
    =
    \left( \frac{2 \pi \Delta}{\omega} \right)^{3N}
\tikzmarkend{z2}
\]
\end{document}

Output 3

enter image description here

[Tex/LaTex] How to adjust the box around the equation

Someone is going to suggest a tikz box with multicoloured translucent rounded corners, but before they do I'll observe that \boxed is a thin wrapper around \fbox so you can use

\setlength\fboxsep{...}

to set the padding inside the box and

\setlength\fboxrule{...}

to set the line thickness.

Best Answer

Related Solutions

TikZ-PGF – Fixing hf-tikz Not Boxing Around Equation

Solution 0

Solution 1 and 2

Solution 3

Codes/Outputs

Code 1 (optional { } argument)

Output 1

Code 2 (catches anything until \tikzmarkend)

Output 2

Code 3 (optional argument with math content)

Output 3

[Tex/LaTex] How to adjust the box around the equation

Related Question

Code 1 (optional `{ }` argument)

Code 2 (catches anything until `\tikzmarkend`)