I need to write something like {\widetilde f}' in my text, but the result looks rather ugly since the prime (derivative) sign is too low. It looks like \widetilde{f'}.

Is there any way to do this properly?

  • Why not \tilde{f'}? – Sigur Jan 2 '14 at 22:16
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    I'd use $\tilde{f}'$, so there wouldn't be any ambiguity about it being the derivative of “tilde f” and not ”tilde of the derivative of f”. – egreg Jan 2 '14 at 22:19
  • @egreg: I just prefer \widetilde, but maybe it is indeed better to use \tilde in this case. – xen Jan 2 '14 at 22:38
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    @xen You shouldn't prefer \widetilde; for lowercase letters there's no need for it (and rarely also for uppercase ones). – egreg Jan 2 '14 at 22:39
  • @egreg: Oh, thanks. I didn't know that and I've got used to \widetilde. Although (maybe just for me) even with \tilde it sometimes doesn't look good to write something like \tilde{f}^n. This n "should" be over \tilde, or maybe I'm just wrong here? – xen Jan 2 '14 at 22:49

I'd avoid \widetilde, particularly above an “f”. A decoration (math accent) above a symbol is usually interpreted as a modifier of the symbol itself, so


will be interpreted as “the derivative of f tilde”, rather than “tilde of the derivative of f”.

Should you feel that an ambiguity could arise, it's probably better to add parentheses


rather than raising the prime that could be mistaken for some “tilde prime”.

Below I show some examples.

enter image description here

As you see, raising the prime is not the answer.

  • Many thanks! I just have one question. In comments you said about \widetilde: "for lowercase letters there's no need for it (and rarely also for uppercase ones)". Are there any "rules" when I should use \widetilde? – xen Jan 3 '14 at 11:46
  • @xen Generally, \widetilde should be used only for decorating a group of symbols. – egreg Jan 3 '14 at 11:51

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