Algorithm2e lets you define functions using \SetKwFunction{Fn}{Function} which you can then reference anywhere in the document (not just in an algorithm environment) using e.g. \Fn (which will output Function all nicely typeset in the right font). However, this doesn't work inside captions. For example, the following doc:

  \caption{\Fn, my function}

dies with

Argument of \@caption has an extra }.
<inserted text> 
l.6   \caption{\Fn, my function}

Anyone know what's going on, and how to fix it?

  • 2
    \caption{\protect\Fn my function} should work.
    – Benjamin
    Commented Feb 9, 2016 at 2:32
  • That did work. If you make this a comment an answer, I'll mark it as correct :-)
    – Nate
    Commented Feb 19, 2016 at 4:59

1 Answer 1


The macro has to be protected that it can be used inside caption:

\caption{\protect\Fn my function}

For more information why this is needed have a look at this question:

What is the difference between Fragile and Robust commands?

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