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I have the problem, that I need some quite long formulas and therefore I use breqn. Up till now, there was no problem doing so. But now I have a formula that seems to be too long for breqn. I get some error messages like

! Extra \else.
\eq@trial@b ...e }\eq@trial@succeed \fi \fi \else 
  \eq@trial@save \EQ@last@tr...
l.55 \end{dmath}

These messages are coming several times in the log. The output in the PDF file is correct, but the messages are not pretty. Also I will have to set some even longer formulas and then the output will be even worse.

So my question: Why are there these messages and what can I do against them?

PS: A minimal example. If you disable the landscape environment you will see the error:

\documentclass[a5paper,10pt]{article}
\usepackage{amsmath}
\usepackage{pdflscape}
\usepackage{breqn}

\begin{document}

\begin{landscape}
\begin{dmath}
\stackrel{(4)}{y}_1 = -b_1\,v_1\,\cos x_3 \,\sin x_5 \,x_6^2-c_1\,v_1\,\cos x_3 \,\cos x_5
\,x_6^2+2\,c_1\,v_1\,\sin x_3 \,x_4\,\sin x_5 \,x_6-2\,c_1\,\dot v_1 \,\cos x_3 \,\sin x_5 
\,x_6+c_1\,d_3\,v_1\,\cos x_3 \,\sin x_5 \,x_6+c_1\,d_1\,v_1\,\cos x_3 \,\sin x_5 \,x_6-2\,b_1\,v_1\,
\sin x_3 \,x_4\,\cos x_5 \,x_6+2\,b_1\,\dot v_1 \,\cos x_3 \,\cos x_5 \,x_6-b_1\,d_3\,v_1\,\cos x_3 
\,\cos x_5 \,x_6-b_1\,d_1\,v_1\,\cos x_3 \,\cos x_5 \,x_6-b_1\,c_2\,{v_1}^{2}\,\sin x_3 \,\sin^2 x_5 -
a_3\,c_1\,v_1\,\cos^2 x_3 \,\sin^2 x_5 -c_1\,c_2\,v_1^2\,\sin x_3 \,\cos x_5 \,\sin x_5 b_1\,b_2\,v_1^2\,\sin x_3 \,\cos x_5 \,\sin x_5 +a_3\,b_1\,v_1\,\cos^2 x_3 \,\cos x_5 \,\sin x_5 -
b_1\,v_1\,\cos x_3 \,x_4^2\,\sin x_5 -2\,b_1\,\dot v_1 \,\sin x_3 \,x_4\,\sin x_5 +b_1\,d_2\,v_1\,
\sin x_3 \,x_4\,\sin x_5 +b_1\,d_1\,v_1\,\sin x_3 \,x_4\,\sin x_5 -a_1\,b_1\,v_1\,\sin^2 x_3 \,\sin 
x_5 -a_2\,b_1\,v_1\,\cos x_3 \,\sin x_3 \,\sin x_5 -b_3\,c_1\,v_1\,v_2\,\cos x_3 \,\sin x_5 +b_1\,
\ddot v_1  \,\cos x_3 \,\sin x_5 -b_1\,d_1\,\dot v_1 \,\cos x_3 \,\sin x_5 +b_1\,d_1^2\,v_1\,\cos x_3 
\,\sin x_5 -b_2\,c_1\,v_1^2\,\sin x_3 \,\cos^2 x_5 -c_1\,v_1\,\cos x_3 \,x_4^2\,\cos x_5 -2\,c_1\,
\dot v_1 \,\sin x_3 \,x_4\,\cos x_5 +c_1\,d_2\,v_1\,\sin x_3 \,x_4\,\cos x_5 +c_1\,d_1\,v_1\,\sin x_3 
\,x_4\,\cos x_5 -a_1\,c_1\,v_1\,\sin^2 x_3 \,\cos x_5 -a_2\,c_1\,v_1\,\cos x_3 \,\sin x_3 \,\cos x_5 
+b_1\,b_3\,v_1\,v_2\,\cos x_3 \,\cos x_5 +c_1\,\ddot v_1  \,\cos x_3 \,\cos x_5 -c_1\,d_1\,\dot v_1 
\,\cos x_3 \,\cos x_5 +c_1\,d_1^2\,v_1\,\cos x_3 \,\cos x_5 -d_1^3\,x_2
\end{dmath}
\end{landscape}

\end{document}
share|improve this question
    
Shouldn't it be the other way around - leaving this as-is in the example causes a problem. –  Werner Aug 30 '11 at 20:10
    
OK, throw the package out and the two lines. Then I get some errors (texlive 2011) –  Christian Wolf Aug 30 '11 at 20:13
    
do you need the equation number? If not use simply $...$ instead of dmath –  Herbert Aug 30 '11 at 20:19
    
Commenting out the landscape environment, I get the following error: ! Undefined control sequence. \eq@dense@enough@b ...m@b <\dim@c \true@true@true \else \false@true@false \fi l.25 \end{dmath} –  Gonzalo Medina Aug 30 '11 at 20:21
    
@Herbert: $..$ does not break the equation, or am I wrong? –  Christian Wolf Aug 30 '11 at 20:25

1 Answer 1

Adding the definition

\makeatletter
\def\true@true@true{\fi\fi\iftrue\iftrue\iftrue}
\makeatother

corrects the error under TeX Live 2011.

Loading the pdflscape package before the breqn package seems to solves the problem under TeX Live 2009 (tested on ScribTeX).

share|improve this answer
1  
Thanks, this has now been fixed in the source. –  Will Robertson Aug 31 '11 at 1:08

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