I apparently can't see the difference in a compilation (pdflatex) between `\mathrm`

and `\operatorname`

. So, as in the title the question is: is there a difference? Which one is preferable in what occasions?

# [Tex/LaTex] What’s the difference between \mathrm and \operatorname

amsmathmath-modemath-operators

## Best Answer

There are many differences. The main one is in the fact that

`\mathrm{xyz}`

behaves like an ordinary letter, while`\operatorname{xyz}`

behaves like function names such as`\sin`

. Here's an illustrationwhere it's clear that the second line is typeset wrong. Even if your "operator" requires parentheses after it, it should be

`\operatorname`

, as the third summand shows, where a thin space separates the coefficient from the operator.Another subtle difference is in how some characters are interpreted in

`\mathrm`

and in`\operatorname`

. Suppose you have an operator to be called "pre-norm", with a hyphen. Here's the exampleand now it's clear what is to be used. Indeed

`\operatorname`

(and the same holds for macros defined with`\DeclareMathOperator`

) treats punctuation symbols in a special way;`\mathrm`

, instead, treats them as math symbols.