[texhax] 3x3 array of alighned equations

[Philip G. Ratcliffe]

> [a lot of snipping]
>
> p.s. Using the subequations environment doesn't work, it simply 
> sets the tags to be (1a), (1b) and (1c) for the first, second and 
> third lines, respectively.

Ah, but did you try this (N.B. with NO \stepcounter{equation})?

\begin{subequations}
  \label{all}
  \begin{alignat}{3}
    a&=b    & &=c & &=d \tag{\theequation a,b,c} \\
    a&=bbbb & &=c & &=d \tag{\theequation d,e,f} \\
    a&=bb   & &=c & &=d \tag{\theequation g,h,i}
  \end{alignat}
\end{subequations}
Here we had Eq.~\eqref{all} containing, for example, Eq.~(\ref{all}a).

It's still pretty ham-fisted but it does do what you want.

Cheers,  Phil