I'm using overleaf and getting errors while trying to run

\subsection{Decomposition of circular functions as a product of elemental trigonometric functions \footnote{We take elemental trigonometric functions to mean circular functions having a period of $2 \pi$ (i.e. $\sin x$, $\cos x$).}} 

The error im getting is:

Argument of \@sect has an extra }.

<inserted text> 
l.24 ...od of $2 \pi$ (i.e. $\sin x$, $\cos x$).}}

I've run across a `}' that doesn't seem to match anything.
For example, `\def\a#1{...}' and `\a}' would produce
this error. If you simply proceed now, the `\par' that
I've just inserted will cause me to report a runaway
argument that might be the root of the problem. But if
your `}' was spurious, just type `2' and it will go away.
 main.tex, line 24

Runaway argument?

{\normalfont \large \bfseries }{\@xfootnote }\def \reserved@b {\stepcounter \ETC.
! Paragraph ended before \@sect was complete.
<to be read again> 
l.24 ...od of $2 \pi$ (i.e. $\sin x$, $\cos x$).}}

I suspect you've forgotten a `}', causing me to apply this
control sequence to too much text. How can we recover?
My plan is to forget the whole thing and hope for the best.
  • 2
    Try with \subsection[<ToC entry>]{<regular title>}; the issue is probably related to using a fragile argument (something like \footnote) inside the sectional title... – Werner Dec 18 '19 at 2:05
  • 2
    Welcome to tex.sx. As @Werner says, this is probably related to \footnote. In addition to providing the optional <TOC entry> (you really don't want a footnote marker in the TOC), you might need to add \protect just before \footnote. – barbara beeton Dec 18 '19 at 2:27
  • 5
    Does this answer your question? Footnote in sub-section title – Vincent Dec 18 '19 at 2:31
  • I have put the \protect command before \footnote and everything seems to work just fine. Thanks for the answers – maths Dec 19 '19 at 17:17
  • please paste the entire page. – Vaman Kulkarni May 29 at 10:25

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