# Invisible floor and ceil math delimiters

Why the floor and ceil math delimiters don't display?

Code:

\starttext
\startformula
\Bigl\lfloor \frac{x}{y}\Bigr\rfloor
\stopformula
\startformula
\Bigl\lceil \frac{x}{y}\Bigr\rceil
\stopformula
\stoptext


• It displays for me.
– user11232
May 5, 2015 at 12:39
• ...but not for me on TexLive 2014, mac os x, using context as the command to process the given input. May 5, 2015 at 12:57
• for me \left\lfloor ... \right\rfloor works ok. May 5, 2015 at 13:03
• Maybe you need additional fonts. May 5, 2015 at 13:27
• @Sigur: No, \left and \right work so you do not need additional fonts. It is a bug of ConTeXt. May 6, 2015 at 9:51

This was a bug! It has been fixed in the beta ver: 2015.5.11.

If you are using ConTeXt standalone, you can update your distribution and these will work. The fix would also be part of TL2015.

In case you are wondering, why such this bug existed, ConTeXt has an experimental feature (motivated by MathML fences). For example, if you want the \lfloor ... \rfloor to appear in blue, you can use:

\setupmathfence[floor][color=blue]
\starttext
$\left\lfloor x \right\rfloor$
\stoptext


This only works with \left..\right and not \big etc. The above example gives

It is also possible to use this to define new fences (what LaTeX calls PairedDelimiters). For example,

\definemathfence [ABS][bar][ command=yes, color=blue]


defines a command \ABS{...} that is equivalent to \fenced{bar}{...}, which, in-turn, is equivalent to \left| ... \right|.

Some of the delimiters were missing and as a side-effect, \big\lfloor was not working.