LyX ⇒ Integrals already defined

[GianGesù]

Hi!

I'm a T.A. for a calculus course and I like writing the homework solutions in LyX so the students can check them out. I usually load amsmath when I write this kind of documents and I didn't have any problem until now when I tried to write an integral. The error that LyX gives is:

Code: Select all

LaTeX Error: Command \iint already defined.
LaTeX Error: Command \iiint already defined.
LaTeX Error: Command \iiiint already defined.

Even if I only use a single integral \int in the document. Below, in the "Description" window, LyX gives:

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...d{\iint}{\DOTSI\protect\MultiIntegral{2}}
                                                  
Your command was ignored.
Type  I <command> <return>  to replace it with another command,
or  <return>  to continue without it.

I'm using MikTeX 2.9 and LyX 2.0.5.1. The document I wrote when I got these error messages was:

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\usepackage{amsmath}

\begin{document}
If I load \emph{amsmath}, \LyX{} won't compile the file when I write
an integral like $\int\mathrm{d}V$.
\end{document}

I'd appreciate your help. Thank you.

[cgnieder]

Hi and welcome to the LaTeX community?

Do you by any chance use the newtx fonts for your document? This is a common error when they're combined with amsmath:

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\documentclass{article}
\usepackage[T1]{fontenc}

\usepackage{newtxmath}
\usepackage{amsmath}

\begin{document}

text

\end{document}

This can be prevented when amsmath is loaded before newtxmath.

If this doesn't help it would be easiest if you could attach a minimal .lyx file (cf. Minimal Working Example) that we could test.

Regards

[GianGesù]

Thank you, cgnieder!

I have never used any newtx font. What I do is to define commands for symbols I use constantly through the document I write, so I need to load amsmath to use \DeclareMathOperator. I send you a very brief example, hoping it's a well suited MWE.

Regards,
GianGesù

[cgnieder]

There should be no need to load amsmath via \usepackage. I didn't find where exactly the conflict exactly comes from but I suspect that it is to do with the esint package. your MWE compiles if I remove the

Code: Select all

\usepackage{amsmath}

line from the preamble and change LyX' math settings from automatic to explicit:

lyx_amsmath.png (30.89 KiB) Viewed 18497 times

It did also work with all settings enabled (explicitly)

Regards

[GianGesù]

Thank you, cgnieder --once again!

Everything's working perfectly now.

Regards,
GianGesù