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

Aditya Mahajan 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The definition from m-newmat is at least partly superceded by the new core math definitions Hans added last week, so a new implementation would be better.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? Aditya