# 3 equations + vertical dots

I was googling the way of adding 3 dots between two equations, I found this question> (Vertical alignment of dots in equation)

What I want:

• Three equations.
• Between equation 2 and 3 I want 3 dots.

When I implemented their way into my equation, I got a really funny equation:

\begin{alignat}{1}
x_{0} = y + m_{0} \\
x_{1} = y + m_{1} \\
\vdotswithin{x_{1} = y + m_{1}}
x_{n} = y + m_{n}
\end{alignat}


the result:

questions:

1. how do i make these dots above the third equation and in the center?

2. why do I have to write the equation twice, once with
\vdotswithin{equation} and once without it? is there another way?

3. how do I only get equation numbers for the actual equations without the dots? because when i implement it the dots are numbered as an equation.

Edit 1: Replaying to @Thomas's answer this:

\begin{align*}
x_{0} &= y + m_{0} \\
x_{1} &= y + m_{1} \\
&\vdots\\
x_{n} &= y + m_{n}
\end{align*}


produces this:

the dots are still not aligned to the equal sign or at least the middle of the equation. How can i modify that?

• See the modified answer. – Thomas Apr 23 '16 at 11:53
• You have to use &\vdotswithin{=}. – Manuel Apr 23 '16 at 12:12

I think you can simplify a bit and use something like this (from the amsmath package):

\begin{align}
x_{0} &= y + m_{0} \\
x_{1} &= y + m_{1} \\
&\;\;\vdots \notag \\
x_{n} &= y + m_{n}
\end{align}


The notag command removes the equation numbering from the line with the vertical dots. I am sure there is a way of adding the exact amount of white space (equal to half the width of the equals sign) to center the dots under the =, but this does the job in a rather simple manner.

EDIT (with inspiration from Manuel's comment)

The mathtools package provides two versions of the vdotswithin command (notice the missing \\ in the short version).

\begin{align}
x_{0} &= y + m_{0} \\
&\shortvdotswithin{=}
x_{1} &= y + m_{1} \\
&\vdotswithin{=} \notag \\
x_{n} &= y + m_{n}
\end{align}


Resulting in:

You don't have to write the equation twice: you have to write the relation symbol w.r.t. which the dots will be centred. Illustration with \vdotswithin and \shortvdotswithin:

\documentclass{article}

\usepackage{mathtools}

\begin{document}

\begin{align}
x_{0} & = y + m_{0} \\
x_{1} & = y + m_{1} \\
& \vdotswithin{ = }\notag \\
x_{n} & = y + m_{n}
\end{align}

\begin{align}
x_{0} & = y + m_{0} \\
x_{1} & = y + m_{1} \\
& \shortvdotswithin{ = }\notag \\[-3.5ex]
x_{n} & = y + m_{n}
\end{align}

\end{document}


• I am sorry for the overlap, but I was editing my answer while you posted yours so I didn't notice. What is the reason for \\[-3.5ex] after the short version? – Thomas Apr 23 '16 at 12:27
• It's to get the vdots vertically centred between eqs (5) and (6) – Bernard Apr 23 '16 at 12:31
• @Thomas: It seems there's a detail I hadn't seen in the use of \shortvdotswithin… I've learnt something today :o) – Bernard Apr 23 '16 at 12:34
• It looks like it. Although I think including the linebreak (without adjusting space afterwards) would add to the consistency of the notation. – Thomas Apr 23 '16 at 12:37
• What I couldn't find is how to change the vertical spacing in \shortvdotswithin – a little too tight for my taste. It works with a system key=value, but when I write modifications in my preamble, the compiler complains… – Bernard Apr 23 '16 at 12:53