You may have felt lost in the sea of LaTeX packages related to AMS – American Mathematical Society. Which ones do you need? How do they include each other?

1 The Main amsmath Package and What It Includes

The main package that you'll get to use is amsmath. While it's probably convenient to just include it to cover the great majority of purposes and needs, you may choose to more restrictively \usepackage some of the smaller packages that it includes:

• The amsopn package provides the \DeclareMathOperator command which lets you declare custom mathematical operators.
• The amstext package provides the \text command for writing plain text in mathematical expressions, text which won't render in italic with weird spacing.

2 Additional Packages

The following packages are not included in the amsmath package and you may want to \usepackage them in addition:

• The amscd package for drawing commutative diagrams with the CD environment.
• The amdthm package to declare theorem-like structures. It comes with a proof environment.
• The amsxtra package provides tools for backward compatibility.
• The upref package for having \ref print cross-reference numbers in an upright font, regardless of the context.
• The amsfonts package provides various fonts (e.g. \mathfrak and \mathbb).
• The amssymb package is automatically loaded by amsfonts and provides symbols.
• The eufrak package defines \mathfrak (which also comes with amsfonts).
• The eucal package to have \mathcal use the Euler script instead of Computer Modern.

3 In Practice

Consequently, you may only need to include the following couple of lines in your preamble:

\usepackage{amsmath}
\usepackage{amsfonts}

4 References

• Frank Mittelbach, Michel Goossens & Alexander Samarin, The L^AT_EX Companion