## Stata 15 help for functions

```
[FN] Functions by category

Description

Quick references are available for the following types of functions:

+--------------------------------------------------------+
| Type of function             | See help                |
|------------------------------+-------------------------|
| Date and time                | datetime functions      |
|                              |                         |
| Mathematical                 | mathematical functions  |
|                              |                         |
| Matrix                       | matrix functions        |
|                              |                         |
| Programming                  | programming functions   |
|                              |                         |
| Random-number                | random-number functions |
|                              |                         |
| Selecting time spans         | time-series functions   |
|                              |                         |
| Statistical                  | statistical functions   |
|                              |                         |
| String                       | string functions        |
|                              |                         |
| Trigonometric                | trigonometric functions |
|                              |                         |
+--------------------------------------------------------+

Introduction

Functions are used in expressions, which are abbreviated exp in syntax
diagrams.  For example, a simplified version of generate's syntax is

generate newvar = exp

and thus, one might type "generate loginc = ln(income)".  ln() is a
function.

Functions may be specified in any expression.  The arguments of a
function may be any expression, including other functions.

A function's arguments are enclosed in parentheses and, if there are
multiple arguments, separated by commas.

Functions return missing (.) when the value of the function is undefined.

Examples

. generate y = sqrt(abs(z*z-x*x-y))

. gen str20 new = cond(sex=="m","Mr. ", "Ms. ") + proper(name)

```