Introduction to the \eqalign Tex Command

The \eqalign Tex command is a powerful tool for formatting and aligning mathematical equations in LaTeX. It allows you to align multiple equations on a specific symbol or operator, making it easier to understand complex mathematical expressions. In this article, we will explore the features of the \eqalign command, and how to use it effectively.

Syntax

The syntax for the \eqalign command is as follows:

\eqalign{<equation line 1> \cr <equation line 2> \cr ... <equation line n>}

Each equation line is separated by the \cr command (which stands for "carriage return"), and can contain any valid LaTeX mathematical code.

Aligning Equations

One of the primary benefits of using the \eqalign command is the ability to align equations on a specific symbol or operator. To do this, you simply add an ampersand symbol (&) at the point where you wish to align the equations. For example:

\eqalign{x &= y + z \cr
          a &= b - c \cr
          p &= q * r}

This code will align the equations on the equals sign (=), resulting in the following output:

x = y + z
a = b - c
p = q * r

Note that the ampersand symbol must be placed at the same position in each equation line in order to properly align the equations.

Centering Equations

By default, the \eqalign command will align equations to the left-hand side of the page. To center the equations, you can use the \centering command inside the \eqalign block, like so:

\eqalign{\centering x + y + z &= a + b + c \cr
          \centering p - q &= r - s}

This code will center the equations, resulting in the following output:

      x + y + z = a + b + c
            p - q = r - s

Wrapping Equations

If an equation is too long to fit on one line, you can use the \hfil\break command to break the equation into multiple lines. For example:

\eqalign{\hfil (x + y + z) * (a + b + c) &= \cr
          \hfil x * a + x * b + x * c + y * a + y * b + y * c + z * a + z * b + z * c &= \cr
          \hfil x * (a + b + c) + y * (a + b + c) + z * (a + b + c) &= \cr
          \hfil (x + y + z) * (a + b + c)}

This code will wrap the equation onto multiple lines, resulting in the following output:

(x + y + z) * (a + b + c) =
 x * a + x * b + x * c + y * a + y * b + y * c + z * a + z * b + z * c =
 x * (a + b + c) + y * (a + b + c) + z * (a + b + c) =
 (x + y + z) * (a + b + c)

Conclusion

The \eqalign command is a powerful tool for formatting and aligning mathematical equations in LaTeX. By taking advantage of its features, you can create clear and easy-to-read equations that will help you communicate your ideas more effectively.