Re: Missing \dddot and \ddddot

[Aditya Mahajan <adityam@umich.edu>]

On Thu, 14 Sep 2006, Hans Hagen wrote:

> Aditya Mahajan wrote:
>> On Thu, 14 Sep 2006, WN wrote:
>>
>>
>>> Hello,
>>> I need to use \dddot and \ddddot in one of my documents, does anyone
>>> know how to
>>> define these math symbols.
>>>
>>
>> The trouble is that most fonts do not contain these accents.
>> amsmath.sty gets over this definition by faking these symbols. It is
>> easy to port these definitions to context.
>>
>> amsmath.sty definition
>>
>> \newcommand{\dddot}[1]{%
>>    {\mathop{#1}\limits^{\vbox to-1.4\ex@{\kern-\tw@\ex@
>>     \hbox{\normalfont ...}\vss}}}}
>> \newcommand{\ddddot}[1]{%
>>    {\mathop{#1}\limits^{\vbox to-1.4\ex@{\kern-\tw@\ex@
>>     \hbox{\normalfont....}\vss}}}}
>>
>>
>> Converting to context
>>
>> %--------------------%<------------------------------------
>> \unprotect
>>
>> % The true copy of amsmath definitions
>> \def\amsdddot {\limits^{\vbox to -1.4ex{\kern-2ex\hbox{\the\textfont\z@ ...}\vss}}}
>> \def\amsddddot{\limits^{\vbox to -1.4ex{\kern-2ex\hbox{\the\textfont\z@....}\vss}}}
>>
>> % I do not understand why you need to give negative height
>>
> \setbox\scratchbox{..} \ht\scratchbox0pt \dp\scratchbox-2pt

I was wondering why amstex definition does this, as the 1.4ex depth 
was too big. Then I realized that it is not 1.4ex but 1.4\ex@ with 
\ex@ as .2326ex. ughh....the ugly syntax of plain tex...

So here is a more reliable reproduction of amstex dddot and ddddot

\newdimen\amstexex

\amstexex = .2326ex

\def\dotsadjustbox#1%
   {\vbox to -1.4\amstexex{\kern-2\amstexex
    \hbox{\the\textfont\zerocount#1}\vss}}

\def\dddot#1%
   {{\mathop{#1}\limits^{\dotsadjustbox{...}}}}

\def\ddddot#1%
   {{\mathop{#1}\limits^{\dotsadjustbox{....}}}}

\starttext
$\dddot{a}_{\dddot{b}}$

$\ddddot{a}_{\ddddot{b}}$
\stoptext

Hans, can these definitions be added to the core?

Aditya