Could some­one please de­sign an in­te­gral sign that looks like a Cornu spi­ral? I.e. the usual \int but with curly ends. Typed in LaTeX as \intc, it could go in the esint pack­age or ams­math. It would sig­nify a Feynman path in­te­gral in physics. \intc_a^b \exp{iS[x(t)]}{\cal D}x(t) would sig­nify tak­ing a sum over all paths from point a to point b. Right now one uses just \int_a^b, but it's not a Rie­mann or Lebesgue in­te­gral.

closed as unclear what you're asking by Andrew Swann, Stefan Pinnow, Kurt, Zarko, egreg Oct 30 '16 at 13:36

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  • Welcome to TeX.SX! Please help us to help you and add a minimal working example (MWE) that illustrates your problem. It will be much easier for us to reproduce your situation and find out what the issue is when we see compilable code, starting with \documentclass{...} and ending with \end{document}. You might also want to add to your question how you're including the pdfs etc. – Aradnix Oct 6 '14 at 17:17
  • This is not how this works. A path integral is just an infinite sum over normal Lebesgue integrals. Hence the normal integral sign is perfectly appropriate. The only thing denoted differently is the differential which is abbreviated by \mathcal{D}[x]. – Henri Menke Oct 6 '14 at 17:27
  • Well, yes, the action integral S[x(t)] inside the exp can be Lebesgue of course. But if you think about it, \int_a^b doesn't designate the (outside) sum of exponentials of actions over paths very well. The sum is not really just a normal integral. D x(t) helps, but only does half the job, when seen after \int_a^b. \oint won't do it either...LaTeX could do it better now, and it may catch on for some. – Lang Withers Oct 6 '14 at 17:59
  • 3
    Please add an image of what you would like to have. Insert some code to play around with. Like this, it is just a "do-it-for-me!" post. Do you have some references on where this symbol is used? If yes, it could be recommended to the unicode consortium. – LaRiFaRi Nov 14 '14 at 14:51

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