help functions
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Title
[D] functions -- Functions in expressions
Quick references are available for the following types of functions:
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| Type of function | See help |
|--------------------------------------+-------------------------|
| Mathematical functions | math functions |
| | |
| Probability distributions and | |
| density functions | density functions |
| | |
| Random-number functions | random-number functions |
| | |
| String functions | string functions |
| | |
| Programming functions | programming functions |
| | |
| Date and time functions | dates and times |
| | |
| Selecting time spans | time-series functions |
| | |
| Matrix functions | matrix functions |
| | |
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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)
Also see
Manual: [D] functions
Help: [D] egen, [D] generate,
[U] 13 Functions and expressions (expressions),
[U] 13 Functions and expressions (operators)
