By default, equation numbers are place on the right side of an equation for any numbered math environment, such as equation, eqnarray, and align. Surprisingly, the equation number position can is changed through the optional documentclass argument leqno:
Left numbering
\documentclass[leqno]{article}
Right numbering (by default and therefore usually skipped):
\documentclass[reqno]{article}
Here is a minimal working example:
\documentclass[a4paper,12pt, leqno]{article}
\usepackage{amsmath}
\begin{document}
\subsubsection*{Equation:}
\begin{equation}
f(x)=ax^2+bx+c
\end{equation}
\subsubsection*{Align:}
\begin{align}
f_1(x)&=a_1x^2+b_1x+c_1\\
f_2(x)&=a_2x^2+b_2x+c_2
\end{align}
\end{document}
Align is part of the amsmath package which was used here because there are several reasons to avoid eqnarray.
April 5th, 2012 at 1:44 pm
Nice post. I actually found quite useful the avoid eqnarray tip. It’s just one of those things that one struggles with, but you really don’t think there’s an easy way around it. Thanks!
April 5th, 2012 at 2:52 pm
Hmmm, maybe I should summarize the key points of avoid eqnarray in one of my future posts…
Thanks for your comment! Tom.
April 5th, 2012 at 5:56 pm
Yes, it is a great post. I want to change the Chapter numbering to Roman numbers, but keeping Algebraic numbering for Figures, Tables and equations not Roman numbering. How I can do it?
Thanks for any advice,
Humberto
April 8th, 2012 at 12:19 pm
Please see my reply to the same question on another post.
Cheers, Tom.