# Alignment of individual rows in left-justified system of equations

I typeset a general system of equations, which involved some "vertical" dots. But I can't figure out how to make those dots appears in the center. Moreover, I actually want to make two streams of vertical dots. Would appreciate some help.

\begin{equation}
\begin{cases}
u_{1,t}=\nabla\cdot D(u_{1})\nabla u_{1,t}+f_1(c_1, \dots, c_m, u_1, \dots, u_n)\\
\vdots \\
u_{n,t}=\nabla\cdot D(u_{n})\nabla u_{n,t}+f_2(c_1, \dots, c_m, u_1, \dots, u_n)\\
c_{1,t}=\Delta c_1-g_1(c_1, \dots, c_m, u_1, \dots, u_n)\\
\vdots \\
c_{m,t}=\Delta c_m-g_m(c_1, \dots, c_m, u_1, \dots, u_n)\\
\end{cases}\tag{II}
\end{equation} I would not uses cases for this, which is better suited for use on the right-hand side of an equation. Rather I would use an aligned block, aligning on the equality signs, and enclosed in a

\left\{  ...  \right.


pair to produce the left brace. MadyYuvi's suggestion to use \vdotswithin is also a good aid. \documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{equation}
\left\{
\begin{aligned}
u_{1,t}&=\nabla\cdot D(u_{1})\nabla u_{1,t}+f_1(c_1, \dots, c_m,
u_1, \dots, u_n)\\
&\vdotswithin{=} \\
u_{n,t}&=\nabla\cdot D(u_{n})\nabla u_{n,t}+f_2(c_1, \dots, c_m,
u_1, \dots, u_n)\\
c_{1,t}&=\Delta c_1-g_1(c_1, \dots, c_m, u_1, \dots, u_n)\\
&\vdotswithin{=} \\
c_{m,t}&=\Delta c_m-g_m(c_1, \dots, c_m, u_1, \dots, u_n)\\
\end{aligned}
\right.
\tag{II}
\end{equation}

\end{document}


Use \vdotswithin tag which comes along with the package mathtools, and the codes are follows:

\documentclass{book}
\usepackage{mathtools}
\begin{document}

\begin{equation}
\begin{cases}
u_{1,t}=\nabla\cdot D(u_{1})\nabla u_{1,t}+f_1(c_1, \dots, c_m, u_1, \dots, u_n)\\
\vdotswithin{u_{n,t}=\nabla\cdot D(u_{n})\nabla u_{n,t}+f_2(c_1, \dots, c_m, u_1, \dots, u_n)} \\
u_{n,t}=\nabla\cdot D(u_{n})\nabla u_{n,t}+f_2(c_1, \dots, c_m, u_1, \dots, u_n)\\
c_{1,t}=\Delta c_1-g_1(c_1, \dots, c_m, u_1, \dots, u_n)\\
\vdotswithin{u_{n,t}=\nabla\cdot D(u_{n})\nabla u_{n,t}+f_2(c_1, \dots, c_m, u_1, \dots, u_n)} \\
c_{m,t}=\Delta c_m-g_m(c_1, \dots, c_m, u_1, \dots, u_n)\\
\end{cases}\tag{II}
\end{equation}

\end{document}


Output: Please read the documentation of mathtools package, page number 22 for further details

• I'm using Kile (XeLaTeX). For some reason it complains when I try to compile a file with it: l.263 \vdotswithin\\ ! Misplaced \cr. \reserved@b ->\ifnum 0=`{\fi }\${}\cr – sequence Oct 9 '19 at 15:34
• @sequence The mentioned error may be due to version issue, please update with the current setup and try... – MadyYuvi Oct 10 '19 at 4:40
• Thanks, it looks like it is working now. – sequence Oct 10 '19 at 4:49