# [NTG-context] Substack in Context

Wed Feb 22 12:00:31 CET 2006

<--- On Jan 28, Taco Hoekwater wrote --->

>>> The definition from m-newmat is at least partly superceded by the
>>> new core math definitions Hans added last week, so a new implementation
>>> would be better.
>>
>> Can you suggest something?
>
> Like this maybe?
>
> \def\substack#1%
>   {\begingroup
>    \let\\\cr
>    \startmathmatrix #1\stopmathmatrix
>    \endgroup}
>
> Probably needs a bit of tweaking to make it look better
> (perhaps a [strut=no] parameter?).
>

<--- On Jan 28, Vit Zyka wrote --->

> What about use math primitive \atop:
>
> \def\substack#1%
>    {\begingroup
>     \let\\\atop
>     #1
>     \endgroup}
>

Sorry for not getting back for almost a month. Both suggestions work
only partially. Consider

\startmathformula
\sum_{%
\startmathmatrix
i = 1 \NR i \neq n \NR i \neq m
\stopmathmatrix
}a_i
\stopformula

As Taco mentioned, the spacing is bad.

\atop gives correct spacing but you need to put subscripts in groups
of two.

\startformula
\sum_{ {i = 1 \atop i \neq n}\atop i \neq m } a_i
\stopformula

Moreover, the font size is incorrect in both cases. Compare with the
size of the subscript in \sum_{i = 1}.

Any suggestions?