# Help/Adv. Equations

## Multiple Lines in Equations

Multiple lines in equations are handled between the delimiters **\begin{align}** and **\end{align}** with each line separated from the next with the use of '\\' at the end. Each line can be aligned at a location designated by '&' on each line.

For example, the equation:

was typed as follows:

**<math>**

**\begin{align}**

**& \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\**

**& \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\**

**\end{align}**

**</math>**

The same multi-line equation can be numbered, by enclosing the whole of the "align" inside an Equation template, as shown below:

(25) |

was typed as follows:

**{{Equation|<math>**

**\begin{align}**

**& \text{if} \quad r\le 1.57\quad {{f}_{w}}=0.3 \\**

**& \text{if} \quad r>1.57\quad {{f}_{w}}=0.00251\ \exp \left( 5.21\ {{r}^{-0.19}} \right) \\**

**\end{align}**

**</math>|25}}**