non-italic capital greek letters

Question

I am using svjour3 class to draft my manuscript and have many \usepackage in it. The capital greek letters are rendered italic in the output. svjour3 could be obtained from journal website

Following is a example (the symbols are italic even when no extra packages are loaded)

\documentclass{svjour3}
\usepackage{amsmath}

\begin{document}
This is just the beginning. \\
This is $\Sigma, \Theta$ in italics and I don't want them to be.

\end{document}

How to avoid this? Please do not suggest \usepackage{upgreek}.

PS: This manuscript I am writing constitutes of abstracts from my thesis, these symbols render correctly in my thesis Latex draft. There would be many other manuscripts and reports simultaneously going on and I want consistency in all. I believe the problem is created by the class file.

Answer 1

The svjour3 class has

\DeclareMathSymbol{\Gamma}{\mathalpha}{letters}{"00}
\DeclareMathSymbol{\Delta}{\mathalpha}{letters}{"01}
\DeclareMathSymbol{\Theta}{\mathalpha}{letters}{"02}
\DeclareMathSymbol{\Lambda}{\mathalpha}{letters}{"03}
\DeclareMathSymbol{\Xi}{\mathalpha}{letters}{"04}
\DeclareMathSymbol{\Pi}{\mathalpha}{letters}{"05}
\DeclareMathSymbol{\Sigma}{\mathalpha}{letters}{"06}
\DeclareMathSymbol{\Upsilon}{\mathalpha}{letters}{"07}
\DeclareMathSymbol{\Phi}{\mathalpha}{letters}{"08}
\DeclareMathSymbol{\Psi}{\mathalpha}{letters}{"09}
\DeclareMathSymbol{\Omega}{\mathalpha}{letters}{"0A}

because the editorial policy of Springer wants uppercase Greek letters in italics by default.

Use \mathrm{\Gamma} and so on if you want them upright. However, you shouldn't be using svjour3 for other purposes than submissions to Springer journals.

Answer 2

As usual, egreg has a great answer, but I’ll supplement it with a bit of information on how you can select between upright and italic Greek letters.

With a modern toolchain that supports unicode-math, you can select math-style=upright to get all upright letters, and math-style=ISO to get all slanted math letters. Upright numbers and Greek capital letters with all other letters in math mode italicized is the default, but you can select it explicitly with the option math-style=TeX. There is also a fourth math-style=French option. Whatever you select, symbols such as summation and product series remain upright.

Regardless of which option you choose, you can use the commands \upalpha, \upAlpha, and so on, to get upright Greek letters. (There is also the syntax `\symup{pi}.)

Capital Greek letters are upright and other letters are italicized by default in legacy NFSS mode as well. Several packages have the option to change that, including newpx, newtx, isomath and mathastext. Additionally, there are several packages that enable upright Greek letters using commands such as \uppi, including upgreek.

Unfortunately, commands such as \mathrm{\pi} are not supported by all packages. On unicode-math, this selects the text font (or is bugged), and some font packages (such as mathpazo) make it produce garbage. Loading a package that supports \uppi is safer. There are additionally a number of fonts to load Greek letters in text mode, although if you want to write Greek words and not just math symbols with legacy packages, you are probably loading babel and a LGR-encoded font.