# Double square braces like these ⟦exp⟧?

How do I create mathematical equation double square braces like these ⟦exp⟧ in latex? I failed to find it on google (I created these using word 2010 equation editor). I would like these to be of adjustable height like regular braces if possible.

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Have a look here, and you should be able to quickly find what you are looking for: Exact duplicate of How to look up a math symbol? –  Alan Munn May 15 '11 at 20:41
@Alan: Agree, with the proviso that it took me three goes at drawing the symbol before it came up with the right answer. Detexify ought to have a "wait until I've finished drawing" option. –  Andrew Stacey May 15 '11 at 20:44
@Andrew I use detexify on my phone, so it waits for me. But generally I find it faster to look things up in the Comprehensive Symbols guide. –  Alan Munn May 15 '11 at 20:46
@Andrew: If you keep drawing it reaccesses the image. It came up in my first attempt. Ok, I got `[` after I finished the first part was finished but it jumped to the correct one when I was finished. –  Martin Scharrer May 15 '11 at 20:49
Thanks for all these wonderful suggestion, I will look them up next time :) –  LightningIsMyName May 15 '11 at 20:50
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``````\usepackage{stmaryrd}
...
\$\llbracket a+b\rrbracket\$
``````

You find hundreds of symbols in the "Comprehensive LaTeX List of Symbols" which is on CTAN and, possibly, also on your system (`texdoc symbols`).

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In this modern "internet age", it's useful to point people in the direction of detexify as well as the list of symbols. –  Andrew Stacey May 15 '11 at 20:46
@Andrew: you're probably right, I keep forgetting "detexify". However this resource doesn't suggest `\llbracket` for ⟦, but only `\textlbrackdbl` :( –  egreg May 15 '11 at 20:50
It shows `\llbracket`, but not always depending how I draw it. –  Martin Scharrer May 15 '11 at 20:55
egreg: I agree that it's not always perfect - see my comment on the main question! But one thing that helps is us "training" it (which I did, once it had found the right symbol). –  Andrew Stacey May 15 '11 at 21:03