referencing main subequation

Question

In the following example i labeled each subeqnation.

\begin{subequations}
  \begin{gather}
    R_0 = 0 \label{subeqn:ini-cond-r}  \\
    N_0 = 0 \label{subeqn:ini-cond-n}
  \end{gather}
\end{subequations}

then i could give as reference each equation separately.

What i would like to have, assuming the subequation numbers are 1.1a and 1.1b, is a reference to 1.1 or somehow that LaTeX will show the number 1.1 (It would be nice a solution with hyperref, since i already use it in my work)

Answer 1

You can set an extra label inside the environment subequations but outside the inner math environment. So you will get reference to the parent counter.

\listfiles
\documentclass{report}
\usepackage{amsmath}
\begin{document}
\chapter{foo}
\begin{equation}
A_0=1
\end{equation}

\begin{subequations}
  \label{foo}
  \begin{gather}
    R_0 = 0 \label{subeqn:ini-cond-r}  \\
    N_0 = 0 \label{subeqn:ini-cond-n}
  \end{gather}
\end{subequations}

\begin{equation}
A_0=1
\end{equation}

\eqref{subeqn:ini-cond-r} and \eqref{subeqn:ini-cond-n} and \eqref{foo}
\end{document}

Answer 2

You can put another label to subequations environment.

\begin{subequations}\label{refertothis}
  \begin{gather}
    R_0 = 0 \label{subeqn:ini-cond-r}  \\
    N_0 = 0 \label{subeqn:ini-cond-n}
  \end{gather}
\end{subequations}

Then, you can refer to the equation set via \eqref{refertothis}.