Math & Science ⇒ Equations Alignment Problem

[Cham]

I need to show four equations : two equations on one line, and two other equations on a second line, like this (compilable code):

Code: Select all

\documentclass[12pt,letterpaper]{article}
\usepackage[T1]{fontenc}
\usepackage{amsmath}

\begin{document}

	\begin{align}
		Axy = Bx - 3 &= z = k,
		& Bx - yz &= - 6, \\ \nonumber \\
		C - D &= E + f = 0,
		& Gx - 4y &= 2.
	\end{align}

\end{document}

Here's a preview from the code above :

4equations.jpg (8.83 KiB) Viewed 2817 times

Currently, the equations aren't properly aligned. The two equations on the left side should be centered, as if I was using the gather environment. The two equations on the right side should also be centered. How can I do that ?

This is probably some pretty basic stuff, but I really don't know how to do it !

[Stefan Kottwitz]

For centered blocks within multiline formulas, you could use the gathered environment. For example:

Code: Select all

\documentclass[12pt,letterpaper]{article}
\usepackage[T1]{fontenc}
\usepackage{amsmath}
\begin{document}
\[
  \begin{gathered}
    Axy = Bx - 3 = z = k, \\
    C - D = E + f = 0,
  \end{gathered}
  \hspace{4em}
  \begin{gathered}
    Bx - yz = - 6, \\
    Gx - 4y = 2.
  \end{gathered}
\]
\end{document}

gathered.png (3.3 KiB) Viewed 2809 times

However, it could be hard to number by line on the right if you group it this way. Numbering as a whole is no problem, using an equation environment instead of \[ ... \]. I guess I would change this formula set structure, because I would centered blocks as belonging together, not the lines then which span over different blocks.

Stefan

[Cham]

Hmmm, this is much less "basic stuff" than what I thought.

And yes, line numbering is posing a problem.

So there is no better way to do this ? This is strange.

[Cham]

Actually, what I'm trying to do is this :

I need to present a set of independant equations into some kind of "gather" packs. The equations are not related to each others.

However, I need to save some space, so this is why I placed them in two columns and several lines.

Aligning the equations with the "=" sign is really ugly in this case.

So what's the best way to present them ?