Math & Science ⇒ Numbering subequations within cases-like format

[veks]

Hello!
This is my first post here, I hope I will be clear and follow the rules.

This is an example of the type of equations I would like to put in my document:

Code: Select all

\documentclass{article}
\begin{document}
\begin{equation}
\begin{array}{cl}
\displaystyle{\min_{x}} & f(x) \\ 
\textrm{subject to} & 
\left\{ 
\begin{array}{l}
A x \le b \\ C x = d 
\end{array} 
\right.
\end{array}
\end{equation}
\end{document}

My problem is that I would like to label all subequations, that is, I would like to have (1a) next to f(x), (1b) next to Ax<=b and (1c) next to Cx=d.

If I use align instead of equation+array I can get two labels, one for the cost and one for the constraints, but this is enough for my purpose.
I also played with subnumcases from the cases package, but I don't know how to make it work if the cases are a part of larger equation.

Any help will be much appreciated. Thanks!

[Stefan Kottwitz]

Hi veks,

welcome to the board!

You could use a subequations environment. For example:

Code: Select all

\documentclass{article}
\usepackage{amsmath}
\begin{document}
\begin{subequations}
  \begin{equation}
    \displaystyle{\min_{x}}  f(x) \\
  \end{equation}
  \begin{equation}
    \textrm{subject to} 
    \left\{
    \begin{array}{l}
      A x \le b \\ C x = d
    \end{array}
    \right.
  \end{equation}
\end{subequations}
\end{document}

Stefan

[veks]

Thanks very much for your reply Stefan. Unfortunately, this does not solve my problem.

The code you sent adds (1a) next to the first line (min f(x)) and (1b) next to the second part (list of constraints). What I would like to have is a number next to EACH constraint that is inside the "cases-like" statement, i.e. (1b) next to "Ax<=b" and (1c) next to Cx=d. In other words, I have an array of equations within another array of equations (in order to get the formatting I need), and I would like to number the equations of the inner array.

Thanks!