# How to write maths without italics [duplicate]

Possible Duplicate:
Define additional math operators to be typeset in roman

easy question. I am writing some maths and I want to write the epigraph of a function so I type $epi(\varphi)$ but the epi comes out in italics. I want it to come out as $\log(x)$ would except obviously I cannot use $\epi$. How do I do it?

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## marked as duplicate by Torbjørn T., Alan Munn, egreg, Mike Renfro, Loop SpaceMar 20 '12 at 16:45

Thank you! So I'll create a math operator then. –  Nik Mar 20 '12 at 15:20
We've closed this as a duplicate to make it easier for others looking for how to do this to find the answers. –  Loop Space Mar 20 '12 at 16:46

If you do:

\newcommand{\epi}{\operatorname{epi}}


then \epi will work just as \log does. I believe amsmath also provides:

\DeclareMathOperator{\epi}{epi}


which does the same thing.

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and use \DeclareMathOperator*{\epi}{epi} if you want it to place limits above and below in displayed math. –  daleif Mar 20 '12 at 15:26