4

Please I need to create a formula with specific emplacements, something like enter image description here

I used \usepackage{cases} with the "numcases" environment:

\documentclass{article}
\begin{document}
\usepackage{cases}

\begin{numcases}{}
    \label{e2.1} ..........\\
    \label{e2.2}\quad........\\
    \qquad.........\\
    \label{e2.3}\quad.........\\
    \qquad..........\\
    \qquad.........\\
    \label{e2.4}\quad.........\\
    \qquad.........
    \end{numcases}

\end{document}

I would like to get just three equations (2.1)-(2.3) where (2.1) is centered between the 2nd and 3rd lines, (2.2) centered between the 5th and 6th lines and finally (2.3) instead of (2.8) in the figure.

1
  • 1
    So, a line in the cases should be made with aligned, for example, to group then.
    – Sigur
    Jan 4, 2020 at 15:48

2 Answers 2

5

Something like this?

enter image description here

\documentclass[11pt,a4paper]{report}
\usepackage{amsmath}
\usepackage{cases}
\newcommand{\mydots}{\dots\dots}
\begin{document}
\begin{numcases}{}
\mydots\\
\begin{aligned}
&\quad\mydots\\
&\qquad\mydots
\end{aligned}\\
\quad\mydots\\
\begin{aligned}
&\qquad\mydots\\
&\qquad\mydots
\end{aligned}\\
\quad\mydots
\end{numcases}
\end{document}
4
  • Yes, I have to add "quad" to get my formula? there is a simplet method to get exactly the result of the figure ?
    – M.A
    Jan 4, 2020 at 16:05
  • @M.A Do you want a fixed width dots?
    – Sigur
    Jan 4, 2020 at 16:07
  • Yes please, but (1) and (3) with no numbers.
    – M.A
    Jan 4, 2020 at 16:18
  • 1
    @M.A, to remove a number, simply use \nonumber before \\.
    – Sigur
    Jan 4, 2020 at 16:21
3

I'd use empheq that's much more powerful than cases.

Your requirement about equation numbers can be achieved by nesting aligned.

\documentclass{article}
\usepackage{empheq}

\begin{document}

\begin{empheq}[left=\empheqlbrace]{align}
& \mathstrut ..........
\label{e2.1}
\\
&\begin{aligned}
  &\quad.........\\
  &\qquad.........
\end{aligned}
\label{e2.2}
\\
&\begin{aligned}
  &\quad..........\\
  &\qquad..........\\
  &\qquad..........
\end{aligned}
\label{e2.3}
\\
&\begin{aligned}
  &\quad.........\\
  &\qquad.........
\end{aligned}
\label{e2.4}
\end{empheq}

\end{document}

enter image description here

4
  • The "empheq" environment don't give numbers to the equations.
    – M.A
    Jan 17, 2020 at 18:28
  • @M.A You asked that: "I would like to get just three equations (2.1)-(2.3) where (2.1) is centered between the 2nd and 3rd lines, (2.2) centered between the 5th and 6th lines and finally (2.3) instead of (2.8) in the figure."
    – egreg
    Jan 17, 2020 at 20:18
  • Yes, but when I use your code, I get just the left lbrace and the points without any numbers in the right-hand side.
    – M.A
    Jan 18, 2020 at 9:09
  • @M.A They are in the image, produced with the very same code posted.
    – egreg
    Jan 18, 2020 at 9:31

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