# Capital sigma missing in Euler font

I'm using the Euler font in my equations and it appears that the capital Sigma symbol is missing (a dot is displayed in its place). It appears to be caused by a conflict between euler or eulervm, fontenc and breqn. Here's a minimal example. Any suggestions?

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{eulervm}
\usepackage{breqn}
\begin{document}
$$\Sigma_i$$
\end{document}

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Could you add a minimal example? Both euler and eulervm have a working $\Sigma$ for me... – Seamus Jun 16 '11 at 14:22
very strange. i've just run testfont with eurm10 and euex10, and both the capital sigma and two forms of sum are there; the version accessed is from tex live 2010. please provide a minimum working example to show what package(s) you're using. – barbara beeton Jun 16 '11 at 14:23
I've edited the question to include a minimal example and the conflicting packages. – Derek Jun 16 '11 at 14:42
I've formatted the code sample in your question by indenting it with four spaces in front of each line. You can do that by selecting the code and pressing the {} button. – Jake Jun 16 '11 at 14:43
@egreg -- in fact, breqn redefines not only \Sigma but the whole greek alphabet, making the obvious adjustment of reversing the order of the \usepackage commands inoperative. i think this is not a bug, but a design decision, and would have to ask the maintainer of breqn about it, if it's not obvious from the .dtx file. it's not possible to ask the original author as he died in 2003. however, redefinitions of the greek letters were in a 2002 version of breqn, although in a separate file, not in breqn.sty' itself. – barbara beeton Jun 16 '11 at 15:36

It seems that

\DeclareFlexSymbol{\Gamma}  {Var}{latin}{00}
\DeclareFlexSymbol{\Delta}  {Var}{latin}{01}
\DeclareFlexSymbol{\Theta}  {Var}{latin}{02}
\DeclareFlexSymbol{\Lambda} {Var}{latin}{03}
\DeclareFlexSymbol{\Xi}     {Var}{latin}{04}
\DeclareFlexSymbol{\Pi}     {Var}{latin}{05}
\DeclareFlexSymbol{\Sigma}  {Var}{latin}{06}
\DeclareFlexSymbol{\Upsilon}{Var}{latin}{07}
\DeclareFlexSymbol{\Phi}    {Var}{latin}{08}
\DeclareFlexSymbol{\Psi}    {Var}{latin}{09}
\DeclareFlexSymbol{\Omega}  {Var}{latin}{0A}
\DeclareFlexSymbol{0}{Var}{latin}{30}
\DeclareFlexSymbol{1}{Var}{latin}{31}
\DeclareFlexSymbol{2}{Var}{latin}{32}
\DeclareFlexSymbol{3}{Var}{latin}{33}
\DeclareFlexSymbol{4}{Var}{latin}{34}
\DeclareFlexSymbol{5}{Var}{latin}{35}
\DeclareFlexSymbol{6}{Var}{latin}{36}
\DeclareFlexSymbol{7}{Var}{latin}{37}
\DeclareFlexSymbol{8}{Var}{latin}{38}
\DeclareFlexSymbol{9}{Var}{latin}{39}


after loading breqn is sufficient. Thanks to Gonzalo for providing the clue.

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As barbara beeton mentioned in a comment, flexysym and eulervm don't cooperate. A possible workaroung is to use the savesym package: the idea is to load breqn and then rename the conflicting symbols (the whole Greek alphabet and some others) using \savesymbol. Once this is done, eulervm can be safely loaded.

\documentclass{article}
\usepackage[T1]{fontenc}
\usepackage{breqn}
\usepackage{savesym}
\savesymbol{Gamma}
\savesymbol{Delta}
\savesymbol{Theta}
\savesymbol{Lambda}
\savesymbol{Xi}
\savesymbol{Pi}
\savesymbol{Sigma}
\savesymbol{Upsilon}
\savesymbol{Phi}
\savesymbol{Psi}
\savesymbol{Omega}
\savesymbol{alpha}
\savesymbol{beta}
\savesymbol{gamma}
\savesymbol{delta}
\savesymbol{epsilon}
\savesymbol{zeta}
\savesymbol{eta}
\savesymbol{theta}
\savesymbol{iota}
\savesymbol{kappa}
\savesymbol{lambda}
\savesymbol{mu}
\savesymbol{nu}
\savesymbol{xi}
\savesymbol{pi}
\savesymbol{rho}
\savesymbol{sigma}
\savesymbol{tau}
\savesymbol{upsilon}
\savesymbol{phi}
\savesymbol{chi}
\savesymbol{psi}
\savesymbol{omega}
\savesymbol{varepsilon}
\savesymbol{vartheta}
\savesymbol{varpi}
\savesymbol{varphi}
\savesymbol{infty}
\savesymbol{ldotp}
\usepackage{eulervm}

\begin{document}

$\Sigma_1\Delta_2$

\end{document}


A more definitive solution would be to create a support file in flexysim for eulervm; this doen't seem to be so hard according to the documentation of breqn:

If you find that a particular math font package doesn’t work then please see implementation in flexisym.dtx for how to create a support file—it is easier than one might think. Contributions welcome.

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I lost symbol when I use \leqslant` with your code. How can I get that symbol? – minthao_2011 Apr 16 '15 at 15:00