## Building an Array in Latex

• Expression for an array begins with the following two commands,
\begin{array}{justification}
\end{array}
• All the elements of the array will be placed between the above two commands.
• Array elements can be justified according to your requirement with the use of justification command. l for left, c for centered or r for right justification.
• The parameters passed through the justification command must match with the number of columns.
• Separate the column by an &.
• Seperate the row by a \\.

Look at the table below for examples on building arrays in Latex:

Array Latex Expression Comment

$$\begin{array}{r} a \\ b \\ c \end{array}$$
Plain array

$$( \begin{array}{r} a \\ b \\ c \end{array} )$$
Size of the parenthesis, not enough to enclose all the elements of the array

$$\left( \begin{array}{r} a \\ b \\ c \end{array} \right)$$
Parenthesized array

$$\left[ \begin{array}{rc} a&d \\ b&e \\ c&f \end{array} \right]$$
Note the change in braces[]

$$\begin{array}{|r|c|l|} a&d&g \\ b&e&h \\ c&f&i \end{array}$$
To place vertical bars between the columns

$$\left( \begin{array}{|r|c|l|} a&d&g \\ \hline b&e&h \\ \hline c&f&i \end{array} \right)$$
Use the command \hline, to place horizontal bars between the rows

$$\begin{array}{lcl} z & = & x \\ z & = & x+1 \\ z & = & x+y+2 \end{array}$$
Using array environment to align equations

$$\left( \begin{array}{rcl} aaa&ddd&ggg \\ bb&ee&hh \\ c&f&i \end{array} \right)$$
To clarify the role of justification in the expression. Here, it is {rcl}-1st is right, 2nd is centre and the last is left justified.