[Tex/LaTex] What to do with this hyperref note on amsmath

amsmathequationshyperref

http://www.ctan.org/tex-archive/macros/latex/contrib/hyperref/ has this note copied below:

amsmath
————-
The environments equation and eqnarray are not supported too well.
For example, there might be spacing problems (eqnarray isn't recommended
anyway, see CTAN:info/l2tabu/, the situation for equation is unclear,
because nobody is interested in investigating). Consider using the
environments that package amsmath provide, e.g. gather for equation.
The environment equation can even redefined to use gather:
\usepackage{amsmath}
\let\equation\gather
\let\endequation\endgather`

However, gather and equation environment have the spacing difference as in the answer by Will in align vs equation. Thus my question:

In a document using both hyperref and amsmath, what is the best replacement for equation?

Best Answer

You can see a spacing problem with the following example. The two equations have different spacing with hyperref, but the same spacing (as they should) without it:

\documentclass[fleqn]{article}

\usepackage{amsmath}
\usepackage{hyperref}

\begin{document}

This is a test to check the spacing of the equation environment. Too much?
\begin{equation}
a=b
\end{equation}
This is a test to check the spacing of the equation environment.

This is a test to check the spacing of the equation environment. Too much?%
\begin{equation}
a=b
\end{equation}
This is a test to check the spacing of the equation environment.

\end{document}

But this problem is imo not enough to stop using the equation environment. The other math environments produce too much space if the sentence before the displayed math is short:

\documentclass{article}

\usepackage{amsmath}

\begin{document}

This is a test to check the spacing of the equation environment. Too much? Foo.
\begin{equation}
a=b
\end{equation}
This is a test to check the spacing of the equation environment.

This is a test to check the spacing of the align environment. Too much? Foo.
\begin{align}
a=b
\end{align}
This is a test to check the spacing of the align environment.

\end{document}

which is a much more common problem.

Related Solutions

[Tex/LaTex] Which command should I use for displayed equations

You should use the environments from amsmath. In practice, equation and align are all you usually need.

If you have a single equation, use equation. (Or equation* if you don't want it numbered. Most of the other environments below also have similar * variants.)
If you have a single equation spanning multiple lines, you can either use multline, or use split (inside equation) to have the parts aligned.
If you have multiple equations and you want them to be aligned, use align (or align*).
If you simply want to typeset multiple equations independently (with no alignment), use gather.

There are also flalign and alignat, for some special cases. See the Short Math Guide for LaTeX or texdoc amsldoc (PDF) for more documentation on these environments.

\[ simply says "set the following in a math display", like plain TeX 's $$ (which you should not use), and is equivalent to displaymath. You can use it if you want an unnumbered equation and are too lazy to type (not good practice, semantically speaking), or, I guess, when you're simply "displaying" some long bit of mathematics that isn't an actual equation. And never use eqnarray.

[Tex/LaTex] What’s the difference between split and aligned

One important difference is that split obeys to the centertags (default) or tbtags option. Here is an example

\documentclass[twocolumn]{article}
\usepackage[
%  tbtags,
%  leqno,
]{amsmath}
\begin{document}
\begin{align}
a&=b\\
\begin{split}
c&=d+{}\\
 &=e+{}\\
 &=f
\end{split}\\
g&=h
\end{align}
\end{document}

enter image description here

Now the same with uncommented tbtags:

enter image description here

Now also leqno is uncommented:

enter image description here

To the contrary, aligned will have the equation number according to the vertical alignment option: centered for \begin{aligned}...\end{aligned}, at the top for \begin{aligned}[t]...\end{aligned}, at the bottom for \begin{aligned}[b]...\end{aligned}. Thus it's better to use split whenever possible, if equation numbers are involved. (I rarely use equation numbers, so I usually don't bother.)

Best Answer

Related Solutions

[Tex/LaTex] Which command should I use for displayed equations

[Tex/LaTex] What’s the difference between split and aligned

Related Question