Just do not know how to write the average of a function. The symbol look like a integral sign with a short bar in the middle. It means integral of a function over a ball divide by the measure of the ball, and let the radius of the ball goes to 0+.

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    Have a look to see if the solution given here answers your question: tex.stackexchange.com/questions/46967/…
    – Scott H.
    Feb 18 '13 at 1:59
  • Welcome to TeX.SE. If the above link does not solve your issue, please update the question with more details. Feb 18 '13 at 2:08
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    I think a better answer is this. I tried Detexify and think you might mean \fint
    – DJP
    Feb 18 '13 at 3:33
  • @DJP: Hmm, no, I think the bar shouldn't be slanted. By the way, also this question which asks for the same was closed as duplicate of "How to look up a symbol" (probably due to the OP saying "thank you"). The mother of those questions seems to be Average integral symbol. Feb 18 '13 at 9:53

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