Here is a question that has long been bothering me: what is the correct way to write a function application in \LaTeX?

The simple answer is of course $f(x)$. However, $f\left(x\right)$ delivers a different result (in terms of spacing), even if the height of the argument does not require larger brackets.

In MathML, &ApplyFunction; controls the spacing between the function and its argument like so <mi>f</mi><mo>&ApplyFunction;</mo><mfenced<mi>x</mi></mfenced>.

Is there a similar construct in LaTeX?

Thanks, Sébastien

  • I think the mathtools package fixes the spacing discrepancy between f(x) and f\left(x\right), but I can't find a reference right now. Nov 9, 2016 at 16:35
  • 2
    @ArunDebray, mathtools does not help in this case. If you insist on using left/right (I would not) then you need \mleft/mright (mleftright package). That case that mathtools does fix, is when a fencing macro is made using \DeclarePairedDelimiter then the auto scaller is "fixed", but that is not general.
    – daleif
    Nov 9, 2016 at 18:55

1 Answer 1


Insert \!, this is a negative space exactly equal to the extra space that is inserted between f and \left(. If necessary also at the end.


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