Re: Substack in Context

[Hans Hagen <pragma@wxs.nl>]

Taco Hoekwater wrote:
> Does this look ok?
> (code is not production-ready yet, but seems reasonable to me)
>
> Taco
>
> \def\startsubstack
>    {\begingroup
>     \null
>     \vcenter\bgroup
>     \pushmacro\domatrixNC
>     \let\endmath\relax
>     \def\NC{\domatrixNC}%
>     \def\MC{\domatrixNC\ifmmode\else$\def\endmath{$}\fi}%
>     \global\let\domatrixNC\dodomatrixNC
>     \def\NR{\endmath%
>       \global\let\domatrixNC\dodomatrixNC
>       \vadjust{\kern -.33\bodyfontsize}\crcr}%
>     \mathsurround\zeropoint
>     \everycr\emptytoks
>     \halign\bgroup  \hfil$\scriptstyle ##$\hfil\crcr }
>
> \def\stopsubstack
>    {\crcr
>     \egroup
>     \popmacro\domatrixNC
>     \egroup
>     \endgroup}
>   
without vadjust: (mathstrut + nointerlineskip)

\def\startsubstack
   {\begingroup
    \null
    \vcenter\bgroup
    \pushmacro\domatrixNC
    \let\stopmathmode\relax % to be sure, will go away
    \def\NC{\domatrixNC}%
    \def\MC{\domatrixNC\startmathmode}%
    \global\let\domatrixNC\dodomatrixNC
    \def\NR{\stopmathmode
      \global\let\domatrixNC\dodomatrixNC
      \crcr\noalign{\nointerlineskip}}%
    \mathsurround\zeropoint
    \everycr\emptytoks
    \halign\bgroup\hfil$\scriptstyle\mathstrut##$\hfil\crcr }

\def\stopsubstack
   {\crcr
    \egroup
    \popmacro\domatrixNC
    \egroup
    \endgroup}

> \starttext
>
> \startformula
>    \sum_{%
>      \startsubstack
>       i = 1 \NR
>       i \neq n \NR
>       i \neq m
>       \stopsubstack
>     }a_i
> \stopformula
>
> \stoptext
>
> Aditya Mahajan wrote:
>   
>> <--- 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 The definition from m-newmat is at least partly superceded by the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
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>>     
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