Guide to LaTeX (4th Edition) (Tools and Techniques

266 Chapter 12. Math Extensions with A M S-L AT E X
produces
\[ a_0 + \cfrac{1}{a_1 + \cfrac{1}{a_2 +
\cfrac{1}{a_3 + \cfrac{1}{a_4 +
\dotsb }}}} \]
1
a0 +
1
a1 +
1
a2 +
1
a3 +
a4 + · · ·
If the optional argument pos is missing, the numerator over is centered
on the horizontal rule; otherwise it may take values of l or r to left or
right justify the numerator.
12.2.4 Matrices
Standard L AT E X possesses the environment array for producing arrays
and matrices. The amsmath package provides the additional environments
pmatrix, bmatrix, Bmatrix, vmatrix, and Vmatrix, which automatically
add the enclosing braces (), [], {}, | | and around the array, and in the
right size. For completeness, there is also a matrix environment with no
braces.
In contrast to the standard array environment (Section 4.8.1), these
matrix environments do not require an explicit column specification as
argument. By default, up to 10 centered columns may be used without
any argument. (This maximum number may be changed by giving the
special counter MaxMatrixCols a new value with either \setcounter
or \addtocounter.) Otherwise the matrix environments are used in the
same way as the array environment.
The following example is taken from Section 5.4.3 on page 134 and is
recast here using A M S-L AT E X constructs.
(1,2,...,n)
p1