When I try to use Hendrik Vogt's "\widebar" from Can I get a \widebar without using the mathabx package?, it happens that the output of


becomes as follows:

enter image description here.

The inside index "x" changes. But if I add an extra "{ }" like \widebar{{\mathcal{I}}_{x}}, I will get the right form

enter image description here

I have no idea how to fix the code to make it work without extra "{ }". Could anyone help please?

  • Welcome to TeX.SE.
    – Mico
    Jun 20 at 3:02
  • What is your use case for including the subscript term (here: x) in the argument of \widebar?
    – Mico
    Jun 20 at 3:03
  • Welcome to tex.sx. \mathcal appears to be acting here more like \bfseries than \textbf when those are used in text. If that is so (and I haven't searched out their definitions), the use of the extra braces can't be avoided. Jun 20 at 3:06
  • @Mico If I understand correctly, my use case is writing a mathematic survey about integral closure of ideal sheaves. Jun 20 at 3:14

1 Answer 1


You get the same output as


just with overline above it. You can use


to fix it.

I reproduce the behavior in the example code below to show that, apart from the wrong symbol being used, the output is the same as with \overline.


  \ifdim\ht0=\ht2 #3\else #2\fi
%The bar will be moved to the right by a half of \macc@kerna, which is computed by amsmath:
%If there's a superscript following the bar, then no negative kern may follow the bar;
%an additional {} makes sure that the superscript is high enough in this case:
%Use a separate algorithm for single symbols:
%Enable nesting of accents:
%If there's more than a single symbol, use the first character instead (see below):
    \if#32 \let\macc@nucleus\first@char \fi
%Determine the italic correction:
%Now \dimen@ is the italic correction of the symbol.
    \divide\dimen@ 3
%Now \@tempdima is the width of the symbol.
    \divide\@tempdima 10
%Now \dimen@ = (italic correction / 3) - (Breite / 10)
    \ifdim\dimen@>\z@ \dimen@0pt\fi
%The bar will be shortened in the case \dimen@<0 !
%Place the combined final kern (-\dimen@) if it is >0 or if a superscript follows:
      \ifdim\dimen@<\z@ \let\final@kern1\fi
      \if\final@kern1 \kern-\dimen@\fi
  \let\math@bgroup\@empty \let\math@egroup\macc@set@skewchar
  \mathsurround\z@ \frozen@everymath{\mathgroup\macc@group\relax}%
%The following initialises \macc@kerna and calls \mathaccent:
%If the argument consists of more than one symbol, and if the first token is
%a letter, use that letter for the computations:
    \ifcat\noexpand\first@char A\else







enter image description here

In the third line you can see that the output of \widebar{{\mathcal{I}}_{x}} and of \overline{\mathcal{I}_{x}} are identical.

Compare with the following, based on https://tex.stackexchange.com/a/364929/4427


\DeclareFontShape{U}{mathx}{m}{n}{ <-> mathx10 }{}






enter image description here

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