[NTG-context] underbraces get progressively more misaligned (w/ minimal example)

Wolfgang Schuster schuster.wolfgang at gmail.com
Thu Jul 3 21:21:55 CEST 2014


Am 03.07.2014 um 12:49 schrieb Sanjoy Mahajan <sanjoy at MIT.EDU>:

> I thought the problem might lie with the general
> \definemathunderextensible (math-stc.mkvi), because underbrace is
> defined as
> 
> \definemathunderextensible  [vfenced] [underbrace]    ["FE3DF]          % ["023DF]
> 
> Other underextensibles include \underbar:
> 
> \definemathunderextensible  [vfenced] [underbar]      ["FE33F]
> % ["203E]
> 
> So I tried my example replacing \underbrace with \underbar but the
> alignment comes out fine (and \overbrace works fine too).  So that
> debugging idea didn't work, except to indicate that something special
> about underbrace isn't working right.
> 
> Does anyone have suggestions for further debugging ideas?

math-stc.mkvi:

\unexpanded\def\math_stackers_make_double#top#bottom#category#codepoint#codeextra#text%
  {\begingroup
   \edef\currentmathstackers{#category}%
   \mathstackersparameter\c!left\relax
   \ifmmode\math_class_by_parameter\mathstackersparameter\else\dontleavehmode\fi
     {\edef\currentmathstackers{#category}%
      \edef\m_math_stackers_text_middle {#text}%
      %
      ...
      %
-     \ifx\currentmathtext\empty
+     \ifx\m_math_stackers_text_middle\empty
        \setbox\scratchboxthree\emptyhbox
      \else
        \setmathtextbox\scratchboxthree\hbox{\math_stackers_middletext}%
      \fi
      ...
      \fi}%
  \mathstackersparameter\c!right\relax
  \edef\p_limits{\mathstackersparameter\c!mathlimits}%
  \ifx\p_limits\v!yes
    \expandafter\endgroup\expandafter\limits
  \else
    \expandafter\endgroup
  \fi}

Wolfgang


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