9.2 Displayed Mathematics

One-line unnumbered displayed mathematics can be created using:

\[<maths>\]

where <maths> is the mathematics to be displayed.

Example:

A linear function is a function of the form \[ y = mx + c \]

Output:

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Don't use the displaymath environment or $$...$$ [15]. Use \[ and \] with the amsmath package.

The equation environment provides something similar to \[ \], except that the equation is numbered. Modifying the above example:

A linear function is a function of the form \begin{equation} y = mx + c \end{equation}

results in the following output:

Normal text can be inserted into the equation using

\text{<text>}

which is provided by the amsmath package.

Example:

\[ x = 2 \text{ and } y = -1 \]

results in the following output:

[Re-using an equation]Recall from §5.5. Cross-Referencing that we can cross-reference most things that LaTeX automatically numbers using \ref and \label. Equations can be cross-referenced in the same way:

Equation~\ref{eqn:linear} is a linear function. \begin{equation} \label{eqn:linear} f(x) = mx + c \end{equation}

Image showing typeset output (click here for a more detailed description).

Equation numbers are usually given in parentheses, which can be done using:

Equation~(\ref{eqn:linear})

The amsmath package provides a convenient short cut:

\eqref{<label>}

So the above can be written as:

Equation~\eqref{eqn:linear}

Note:

Both the equation environment and \[...\] are only designed for one line of maths. Therefore you must not have any line breaks or paragraph breaks within them. The following will cause an error:

\begin{equation} ✘ f(x) = mx + c ✘ \end{equation}

Either remove the blank lines or comment them out:

\begin{equation} %✔ f(x) = mx + c %✔ \end{equation}

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