# Re: Arrows in menclose needed?

From: Frédéric WANG <fred.wang@free.fr>
Date: Wed, 19 Jun 2013 11:31:16 +0200
Message-ID: <51C17A64.7000309@free.fr>

On 19/06/2013 01:00, Bruce Miller wrote:
> The problem --- if indeed there is one --- is that this obvious naming
>   "updiagonalarrow"
> doesn't easily extend to putting the arrow head on the other end
> (if we'll ever need to?), nor to adapting to RTL (Does RTL use arrows?),
> or other kinds of arrows, or...
>
Thanks,

Rather than arrows, I guess the real question is how much is needed to
implement cancelto since the need for arrows did not appear until now
(or perhaps some people really want all the arrow notations?):

http://tex.stackexchange.com/questions/11897/draw-a-diagonal-arrow-across-an-expression-in-a-formula-to-show-that-it-vanishes

Currently, MathJax and LaTeXML use "updiagonalstrike" and so they don't
have any arrow head with standard MathML code and can not support RTL
mode. My proposal was just to add one notation "updiagonalarrow" that
adds an arrow head. Unfortunately, as long as we keep  "updiagonalstrike
updiagonalarrow" for backwards compatibility, this won't work in RTL
mode either, even if we say that "updiagonalarrow" have the arrow head
pointing in the direction of the text.

So two questions:

1) LaTeX implements it that as "updiagonalarrow", so is
"downdiagonalarrow" needed (it seems that some people make the arrow
point towards the bottom)?

2) I've never used this cancelto notation in France and I don't know in
which countries it is used. In particular, is it used in countries
writing mathematics from right to left? If not, it can just be drawn the
same way as "updiagonalstrike".

--
Frédéric Wang
maths-informatique-jeux.com/blog/frederic

Received on Wednesday, 19 June 2013 09:34:12 UTC

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