# ! Package amsmath Error: \begin{split} won't work here

I tried to run following code in texmaker,

$$\label{eq4} \begin{split} &R^T \left( \underbar r_{H/G} \times \underline f_H + \underline r_{R/G} \times \underline f_R + \underline \tau_R \right) \\ &= I_G \underline \alpha + \underline \omega \times \left( I_G \underline \omega \right) \end{split}$$


and got following error message,

! Package amsmath Error: \begin{split} won't work here.

What caused this problem and how can I fix it?

Of course, this is part of a document. Therefore, \begin{document} and \end{document} exist at the beginning and the end of the document.

Edited:

@daleif

\documentclass[fleqn,10pt,twocolumn]{ICCAS2020}

\usepackage{lipsum}
\usepackage {subfigure}
\usepackage[T1]{fontenc}
\usepackage[sc]{mathpazo}
\usepackage{cite}
\usepackage {amsmath}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{mathtools}

\begin{document}

\section{EX}

$$\label{eq4} \begin{split} &R^T \left( \underbar r_{H/G} \times \underline f_H + \underline r_{R/G} \times \underline f_R + \underline \tau_R \right) \\ &= I_G \underline \alpha + \underline \omega \times \left( I_G \underline \omega \right) \end{split}$$

\end{document}


Is this what you mean?

@Sebastiano

Thanks for your kind welcome, but your code didn't work for me.

By the way, what does MWE mean?

• Welcome to the TeX.SE. What are your package, please? Jul 1 '20 at 8:37
• Since this compiles just fine for me, we need you to provide (as it tradition on this site) a full (but minimal) example that demonstrates the problem. Thus a document with document class, minimal preamble, that others can copy and test as is. Jul 1 '20 at 8:37
• Thank you very much for your collaboration. Meanwhile delete the blank spaces in \usepackage {amsmath} and in the \usepackage {subfigure}. Jul 1 '20 at 9:08
• Where is ICCAS2020.cls it is not a known class. Jul 1 '20 at 9:29
• @daleif that is a name of a conference where I try to submit my paper. Jul 1 '20 at 9:38

Remove the fleqn option. The class you use essentially do something like this when the fleqn option is active

\usepackage{amsmath}
\input{fleqn.clo}


So if we try

\documentclass{article}
\usepackage{amsmath}
\makeatletter
\input{fleqn.clo}
\makeatother
\begin{document}
$$\label{eq4} \begin{split} &R^T \left( \underbar r_{H/G} \times \underline f_H + \underline r_{R/G} \times \underline f_R + \underline \tau_R \right) \\ &= I_G \underline \alpha + \underline \omega \times \left( I_G \underline \omega \right) \end{split}$$
\end{document}


we get the same error, which goes away if the \input line is removed.

I'd recommend writing to the organisers and showing them your example.

• Thank you very much for your answers. Jul 1 '20 at 11:33

Just your code compile fine for me...I have deleted amsmath and I have leaved the robust command mathtools.

\documentclass[fleqn,10pt,twocolumn]{article}

\usepackage{lipsum}
\usepackage{subfigure}
\usepackage[T1]{fontenc}
\usepackage[sc]{mathpazo}
\usepackage{cite}
\usepackage{graphicx}
\usepackage[english]{babel}
\usepackage{mathtools}

\begin{document}

\section{EX}

$$\label{eq4} \begin{split} &R^T \left( \underbar r_{H/G} \times \underline f_H + \underline r_{R/G} \times \underline f_R + \underline \tau_R \right) \\ &= I_G \underline \alpha + \underline \omega \times \left( I_G \underline \omega \right) \end{split}$$

\end{document}


• Your code worked fine, thanks! It seems ICCAS2020 make the problem... Jul 1 '20 at 9:39