# [texhax] Request informations

Philip G. Ratcliffe philip.ratcliffe at uninsubria.it
Thu Jan 8 12:44:44 CET 2004

> I have a little probleme
> maybe two
>
> the first is that I'm not so clever using Latex
>
> The second is that I like to insert the equations in my
> tesis in the following way of numbering:
>
> equ_1      1.1.a
> equ_2      1.1.b
> equ_3      1.1.c
> equ_4      1.1.d
> equ_5      1.1.e
>
> In this moment with the command subequations and using the
> ansmath package I am able to write in this way
>
> equ_1      1.1a
> equ_2      1.1b
> equ_3      1.1c
> equ_4      1.1d
> equ_5      1.1e

I can see two ways:

1. a local hack - use (every time!)

\bgroup%
\let\oldtheequation\theequation
\def\theequation{\oldtheequation.}
\begin{subequations}
\begin{...}
...
\end{...}
\end{subequations}
\egroup%

2. a global hack - copy the amsmath defnition of the subequations
environment and put the period in yourself - can you see it below?  Beware
though, amsmath may change the original definition in some future upgrade,
without notification!  Note too the \renewenvironment.

\makeatletter
\renewenvironment{subequations}{%
\refstepcounter{equation}%
\protected at edef\theparentequation{\theequation}%
\setcounter{parentequation}{\value{equation}}%
\setcounter{equation}{0}%
\def\theequation{\theparentequation.\alph{equation}}%
\ignorespaces
}{%
\setcounter{equation}{\value{parentequation}}%
\ignorespacesafterend
}
\makeatother

The \makeatletter \makeatother pair are necessary if you put this in your
preamble but not if you put it in, say, 'subeqhack.sty' and load that with
\usepackage{subeqhack} AFTER amsmath.

Cordialmente,  Philip G. Ratcliffe