# I cannot use amsmath package

I try to compile my latex but it doesn't work. It shows the following error

Command \iint already defined. ...d{\iint}{\DOTSI\protect\MultiIntegral{2}}

The command that I'm using is as follows:

\documentclass{aip-cp}

\usepackage{amsmath}
\usepackage[numbers]{natbib}
\usepackage{rotating}
\usepackage{graphicx, amsfonts, amssymb, longtable}
\let\openbox\relax
\usepackage{amsthm, amsthm}

\begin{document}

\end{document}


• aip-cp is not a standard class. You might want to update your question with information where we can get that class. BTW: you can probably just use \let\iint\relax before loading amsmath – daleif Oct 17 '18 at 8:33
• @daleif I reproduced the error using this version of the class. – BambOo Oct 17 '18 at 8:34
• The conflict seems to be between the class and the amsmath package as observed by the OP – BambOo Oct 17 '18 at 8:35
• The class loads txfonts. – Ulrike Fischer Oct 17 '18 at 8:35
• See e.g. tex.stackexchange.com/a/321123/2388 for a possible work around (but better would be if the class wouldn't clash with amsmath). – Ulrike Fischer Oct 17 '18 at 8:38

As mentioned by others this comes from the fact that the class loads txfonts which defines some symbols that amsmath also defines.

Here is an even shorter MWE:

\documentclass[a4paper]{article}
\usepackage{txfonts}
\usepackage{amsmath}
\begin{document}
test
\end{document}


You can use the normal \let...\relax trick to remove these symbols. Turns out there are four:

\documentclass[a4paper]{article}
\usepackage{txfonts}
\let\iint\relax
\let\iiint\relax
\let\iiiint\relax
\let\idotsint\relax
\usepackage{amsmath}
\begin{document}
test
\end{document}

• This document usermanual.wiki/Pdf/guide.451200889.pdf (apparently written by "AIP Tex support") says txfonts (and hyperref) are "optional packages", but it doesn't say how to deselect the option! – alephzero Oct 17 '18 at 10:04
• @alephzero if the class in question is the same as BambOo referred to, then you cannot. BTW: might be an idea to refer to the PDF on their own homepage instead of some website that collects random manuals (that might be out of date). – daleif Oct 17 '18 at 10:11
• Well, that 's what a Google search for "aip-cp" found for me, and it looked likeuseful information. I don't intend to go on a treasure hunt through the AIP site to try to find out more, though. – alephzero Oct 17 '18 at 10:14