Re: underbraces slightly too narrow (with MkIV 2013.05.28)

[Hans Hagen <pragma@wxs.nl>]

On 7/10/2013 2:02 PM, Sanjoy Mahajan wrote:
> In certain cases, display-mathunderbraces are not quite wide enough.
> Here's a minimal example:
>
> ===================
> \starttext
>
> \placeformula\startformula
> \underbrace{15\,\tf cm}_{L}
> \stopformula
>
> \stoptext
> ===================
>
> Using 2013.05.28 00:36 MKIV (from vanilla TL2013), the left brace tip
> starts under the vertical bar of the "1", instead of enclosing the serif
> as well.  The right brace tip ends between the last two tines of the
> "m", instead of enclosing the whole "m" and its serifs.
>
> With 2013.04.09 10:38 MKII, the brace tips extend just slightly beyond
> the "15 cm", which is better.  However, they seem slightly too close.
>
> As a test, I ran the comparable plain-TeX file through LuaTeX and PDFTeX.
>
> ==================
> $$
> \underbrace{15\,\rm cm}_{L}
> $$
>
> \bye
> ==================
>
> The gap between the right brace tip and the text is slightly greater
> (with either LuaTeX or PDFTeX), and it looks right.
>
> (With the 2012.05.30 MKIV on live.contextgarden.net, the result is
> similar to the Lua/PDFTeX versions, though not identical, and also looks
> reasonable.)

it has to do with the fact that we have opentype math fonts now and 
these are not compatible

what you observe is the fact that we have a discrete number of sizes 
till we run out of them and go stretchable

anyhow, i've now defined then in a different way (ok, some more trickery 
had to be applied as it's one of these aspects of open type math that 
still inherits old stuff) so in a next version you can do this:

\setupmathstackers[vfenced][hoffset=10pt]

is it looks like these commands have built-in \limits, these are now set 
for

\overbrace
\overparent
\overbracket
\overbar

\underbrace
\underparent
\underbracket
\underbar

\doublebrace
\doubleparent
\doublebracket
\doublebar

Hans


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