# Greek letters in italic in math equation

I use \Pi and \Sigma in my math equations however, they are not printed in italic like other text. I guess this is because they are symbols and not really text. Putting \textit into the equation has no effect at all. Is there a way to italic these symbols?

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amsmath defines the uppercase greek to follow math alphabet switches:

\documentclass{article}
\usepackage{amsmath}

\begin{document}

$a +\Sigma + \Pi$

$\mathit{a +\Sigma + \Pi}$

\end{document}

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that's fantastic! thanks a lot –  Josh Dec 16 '12 at 17:12
note that the shape of the \mathit a is not" the same as if it's just an ordinary math a (this is true for computer modern, but it may not be for other fonts). \mathit is ordinarily used for italic *words in math environments; single letters are assumed to be variables so the style is adjusted slightly. in this way, a math variable a can be distinguished visually from the article "a" in english; in other languages, other single letters sometimes have non-mathematical semantics. –  barbara beeton Dec 16 '12 at 18:14
\mathnormal will do here as well for the Greek letters and typeset an ordinary math a –  jfbu Dec 16 '12 at 18:27

If you always want the uppercase Greek letter in italics, the easiest method is to load amsmath and change the meaning of \Gamma and similar commands:

\documentclass{article}
\usepackage{amsmath}

\let\Gamma\varGamma
\let\Delta\varDelta
\let\Theta\varTheta
\let\Lambda\varLambda
\let\Xi\varXi
\let\Pi\varPi
\let\Sigma\varSigma
\let\Upsilon\varUpsilon
\let\Phi\varPhi
\let\Psi\varPsi
\let\Omega\varOmega

\begin{document}
$\Gamma \Delta \Theta \Lambda \Xi \Pi \Sigma \Upsilon \Phi \Psi \Omega$
\end{document}


If instead you need both varieties, then input the italic ones with the var prefix: \varGamma and so on.

Note that some font packages, notably kpfonts and fourier, allow for options that decide whether using by default italic Greek uppercase in math.

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Also very nice solution! thanks for that :) –  Josh Dec 16 '12 at 17:13
@Josh Welcome to TeX.SE! When you have enough reputation, don't forget to upvote answers that helped you- it rewards those that looked at your question with 10 reputation points :) –  cmhughes Dec 16 '12 at 17:22
That doesn't work for me. I'm still getting an upright gamma for \Gamma and an italic gamma for \VarGamma. Is there a new solution, to fix that via options of amsmath? Do I have to defeine all my let commands after \begin{document} (which I think quite annoying)? –  LaRiFaRi Jul 19 '13 at 13:55
@LaRiFaRi Please, make a new question with all that's needed to understand the problem. The minimal example above works, so you must have a different set up for your document. –  egreg Jul 19 '13 at 13:57
@AdrianKeister Look at the upgreek package. –  egreg Jun 21 '14 at 19:52