# What's the difference between \DeclareMathOperator and \mathop? [duplicate]

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Is there any difference between

\DeclareMathOperator{\erf}{erf}


and

\def{\erfc}{\mathop{\mathrm{erfc}}}


apart of the fact that \DeclareMathOperator is defined in amsmath package?

## marked as duplicate by GuM, Zarko, Mico, Jesse, Steven B. SegletesJan 7 '17 at 4:33

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• I’m afraid I don’t understand: \mathop is a TeX primitive and does not define a new command/macro. In any case, note that \DeclareMathOperator defines robust commands, and that it has a *-form for managing the behavior of the newly defined operator wrt. “limits”. – GuM Jan 7 '17 at 2:54
• Also, the "Related" is showing mathop shifts the baseline, DeclareMathOperator doesn't. – Teepeemm Jan 7 '17 at 2:56
• @Teepeemm: Thank you for providing the reference to a very similar question. I have got enough reputation to vote to mark the question as a duplicate, as you suggest. – GuM Jan 7 '17 at 3:01