The commands \clap, \llap and \rlap are useful "horizontal" analogues of \smash: they reduce the horizontal width of a box to zero, aligning the box with either the middle, left or right of the typeset contents. Unfortunately they don't work in math mode.

Can someone suggest a math mode macro that has the effect of \clap and friends?

3 Answers 3


The mathtools package contains (among other useful things) the implementations of \mathclap and relatives from Andrew's answer.

  • That should have come up in my search! Strange that it did not. Thanks for filling in. Jul 27, 2010 at 11:57
  • I need examples in the use of the clpa command, rlap and llap cause no issues, but I cannot use clap command in the same manner.
    – Silva
    Apr 16, 2020 at 1:19

I don't know if they are implemented in a specific package (search CTAN), but there's an article in TUGBoat, (TUGboat 22 (2001), 350–352.) that gives an implementation. Here's the article on the author's website:


I suspect that anyone putting this in a package would have used the same names, or at least referred to this article, so searching on CTAN for the command names used there would be a reasonable thing to do.

(Breadcrumb trail: I first learnt of this via this blog post about these commands in iTeX.)

(I'm feeling generous: I just tried the obvious searches on CTAN and nothing came up; so based on that, you should copy the definitions from that article.)


FWIW, in ConTeXt \rlap etc do the right thing in math mode as well. They are defined as


where \domathrlap and \dorlap are roughly equivalent to LaTeX's \mathrlap and \rlap.

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