# chronological order in subequations no alphanumerics (amsmath)

I am searching for a simple way to use subequations, with numerical numbering, so I don't have (1a) (1b) like in the example below etc. I simply want (1) (2) etc

Thanks for the help

\documentclass{article}
\usepackage{amsmath}
\newcommand\StepSubequations{
\stepcounter{parentequation}
\gdef\theparentequation{\arabic{parentequation}}
\setcounter{equation}{0}
}
\begin{document}
\begin{subequations}
\begin{alignat}{2}
\StepSubequations
a&=c(x)  \quad &\text{for} t\geq t_1 \label{eq:subeq2}
\end{alignat}
\label{straincomponent}
\end{subequations}

\end{document}

• Welcome to TeX SX! If that's what you want, don't use the subequations environment and everything will go fine. – Bernard Sep 4 '19 at 12:54
• what would be the best option for equations with double alignment? – user195812 Sep 4 '19 at 13:00
• The second column is , so to say, a comment. What do you mean with ‘option’? – Bernard Sep 4 '19 at 13:05
• its a definition fwhich environment should i use? The function is defined by several sections – user195812 Sep 4 '19 at 13:23

You can have this, based on empheq(which loads mathtools) but you'll lose the possibility to refer to the definition as a whole:

\documentclass{article}
\usepackage{empheq}
}
\begin{document}

\begin{empheq}[left={a=\empheqlbrace}]{alignat=2}
b(x) \quad &\text{for } t<t_1 \label{eq:subeq1}
\\
c(x) \quad &\text{for } t\geq t_1 \label{eq:subeq2}
\end{empheq}

\end{document}


With use of the numcases environment from the cases package:

\documentclass{article}
\usepackage{amsmath}
\usepackage{cases}

\begin{document}

\begin{numcases}{a=}
b(x) & for $t<t_1$        \label{eq:subeq1},\\
c(x) & for $t\geq t_1$    \label{eq:subeq2}
\end{numcases}
From \eqref{eq:subeq1} folows \dots
\end{document}