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I'm trying to get a subequation with 3 lines to have all equations centered horizontally relative to each other.

Right now I have:

\begin{subequations}\label{eq:propArea}
    \begin{alignat}{2}
        A &= first~special~subequation \\
        B &= equation~much~bigger~then~others~above~and~below \\
        C &= smaller~equation
    \end{alignat}
\end{subequations}

enter image description here

As you can see equations are aligned at the & marks.

Using the gathered environment gives:

\begin{equation}\label{eq:propArea}
    \begin{gathered}
        A = first~special~subequation \\
        B = equation~much~bigger~then~others~above~and~below \\
        C = smaller~equation
    \end{gathered}
\end{equation}

enter image description here

As you can see it aligns the equations to their centers, but I loose the sub-numbering that was so useful...

How can I get the two things?

Bernard
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A. Vieira
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  • in a comment to the accepted answer, you say that you probably saw a reference to gather in another question. to get a better overview of what's available, you should read the amsmath users guide; it's not very long. texdoc amsmath. – barbara beeton Aug 27 '17 at 18:15

1 Answers1

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\begin{subequations}\label{eq:propArea}
    \begin{gather}
        A = first~special~subequation \\
        B = equation~much~bigger~then~others~above~and~below \\
        C = smaller~equation
    \end{gather}
\end{subequation}

equation environment has only one number (tag), gathered is designed for in equation, meanwhile gather is for multi line equation where each line is numbered (tagged).

Zarko
  • 296,517
  • Thank you. Now that I think of it, I probably saw that use in other questions I looked at, but I didn't distinguish the names gather and gathered. Had to read your answer twice no catch the difference. lol – A. Vieira Aug 27 '17 at 12:33
  • @A.Vieira ups, i miss your comment: meanwhile gathered is intended for use inside other math environment (as equation for example), gather is not. it had to be used as main math environment. for more information see documentation for mathtools package – Zarko Oct 15 '18 at 23:25