# [NTG-context] \bigl \bigr \big problems

Hans Hagen pragma at wxs.nl
Thu Apr 8 10:31:06 CEST 2010

On 8-4-2010 7:40, Mikael Persson wrote:

> Ok Hans, with the beta from yesterday the absolute values change size,
> but there are some problems still:
>
> 1) The absolute value bars are not just "straight lines" when using
> \big and friends, but som kind of line that is thicker in the middle.
> (zoom i on attached pdf)

this is because lm has no such characters so they are made from the
smaller ones (extensible characters)

in traditional lm this can go unniticed (depends a bit in the exact
definition but in mkii you will see two stacked | just not touching but
in mkiv we use overlap - which is custom in opentype anyway); so what
you observe is an artefact of the viewer - it might be that future
versions of luatex deal better with this as it relates somewhat with how
things are dealt with in the backend but you will observe similar
effects in pdftex

in an earlier version i used rules but then found out that the | has
round tops (ok, i could use pdf literals to draw lines but not today)

> 2) The horizontal spacing in the \big version seems to be bigger than
> for the \bigl/\bigr version (and similar for \Big vs \Bigl/\Bigr). I'd
> expect the same spacing (the l and r are just there for the writer to
> easily see what is left and what is right).

repaired .. (i also added \plainbigmathmode

> 3) I'd expect that \| gives double bars, like the || one get from
> \Vert and not |. This is not so (see the attached file). Moreover, it
> is not possible to do \bigl\Vert right now to get a bigger ||.

i've added double bars so this works:

$\biggl\Vert x^n\biggr\Vert$
$\biggl{||} x^n\biggr{||}$
$\biggl|\biggl| x^n\biggr|\biggr|$

there will be a new beta later today or tomorrow

Hans

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