# 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.

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


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}

\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{document}


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

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

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

\end{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