2

With this code:

Si scriverà, pertanto:

\begin{subequations} \label{eq:laplace-2}
  \begin{align}
    & Z (s^2 M + s C_s + K_s) = Z_u (s C_s + K_s)\\
    & Z_u (s^2 m + s C_s + K_s + K_t) = Z(s C_s + K_s) + K_t Z_r
  \end{align}
\end{subequations}

Isolando nella (\ref{eq:laplace-2}a) il termine $ Z_u $, questo risulta pari a:

I obtain this result:

without

Without the full stop in the middle. Is possible obtain it using the environment subequations?

3
  • 1
    Are you sure you want a full stop hanging from nowhere? By the way, there should be no blank line before the subequations environment (and no colon after “pertanto”). I'd simply add a comma at the end of the first equation and a full stop at the end of the second one. And I'd use gather, rather than align.
    – egreg
    Jan 2, 2016 at 14:47
  • 1
    Also, you should do \label{eq:laplace-2first} in the first row of the align (or gather) and use \eqref{eq:laplace-2first} for the cross reference. This automatically adds the parentheses and takes care of the suffix.
    – egreg
    Jan 2, 2016 at 14:50
  • Thanks @egreg, I will use your useful grammar advices. But, I prefer do not use the `gather' environment, in these equations. Jan 2, 2016 at 15:12

1 Answer 1

2

Doing it is not really difficult, but I don't think the result is pretty, because the period appears to be hanging from nowhere. Just add a row with it and appropriate vertical negative spaces.

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}

\usepackage{amsmath}

\begin{document}

\setcounter{chapter}{2}
\setcounter{equation}{41}

Si scriverà, pertanto,
\begin{subequations} \label{eq:laplace-2}
\begin{alignat}{2}
& Z (s^2 M + s C_s + K_s) = Z_u (s C_s + K_s) \label{eq:laplace-2first} \\[-1.5ex]
&&&\makebox[0pt][l]{\quad.}\notag \\[-1ex]
& Z_u (s^2 m + s C_s + K_s + K_t) = Z(s C_s + K_s) + K_t Z_r
\end{alignat}
\end{subequations}
Isolando nella \eqref{eq:laplace-2first} il termine $ Z_u $, questo risulta pari a

\end{document}

enter image description here

Some points to note:

  1. there should be no blank line before \begin{subequations};
  2. you should use \eqref, that takes care of the parentheses;
  3. the label can better go in the row you want to refer to, so the reference will automatically get the right suffix;
  4. the colon after pertanto is wrong and a comma should be used (or no comma at all).

Here's how I'd realize the text, using natural punctuation.

\documentclass{book}
\usepackage[T1]{fontenc}
\usepackage[utf8]{inputenc}
\usepackage[italian]{babel}

\usepackage{amsmath}

\begin{document}

\setcounter{chapter}{2}
\setcounter{equation}{41}

Si scriverà pertanto
\begin{subequations} \label{eq:laplace-2}
\begin{align}
& Z (s^2 M + s C_s + K_s) = Z_u (s C_s + K_s),\label{eq:laplace-2first} \\
& Z_u (s^2 m + s C_s + K_s + K_t) = Z(s C_s + K_s) + K_t Z_r.
\end{align}
\end{subequations}
Isolando nella \eqref{eq:laplace-2first} il termine $ Z_u $, questo risulta pari a

\end{document}

enter image description here

Actually I'd prefer gather, but with the default line width this particular display would not appear correctly centered, because the second equation is a bit too wide.

1

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