# ATAN (Transact-SQL)

Applies to: SQL Server (all supported versions) Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

A function that returns the angle, in radians, whose tangent is a specified float expression. This is also called arctangent.

## Syntax

``````ATAN ( float_expression )
``````

Note

To view Transact-SQL syntax for SQL Server 2014 and earlier, see Previous versions documentation.

## Arguments

float_expression
An expression of either type float or of a type that implicitly convert to float.

float

## Examples

This example takes a float expression and returns the ATAN of the specified angle.

``````SELECT 'The ATAN of -45.01 is: ' + CONVERT(varchar, ATAN(-45.01))
SELECT 'The ATAN of -181.01 is: ' + CONVERT(varchar, ATAN(-181.01))
SELECT 'The ATAN of 0 is: ' + CONVERT(varchar, ATAN(0))
SELECT 'The ATAN of 0.1472738 is: ' + CONVERT(varchar, ATAN(0.1472738))
SELECT 'The ATAN of 197.1099392 is: ' + CONVERT(varchar, ATAN(197.1099392))
GO
``````

Here is the result set.

``````
-------------------------------
The ATAN of -45.01 is: -1.54858

(1 row(s) affected)

--------------------------------
The ATAN of -181.01 is: -1.56527

(1 row(s) affected)

--------------------------------
The ATAN of 0 is: 0

(1 row(s) affected)

----------------------------------
The ATAN of 0.1472738 is: 0.146223

(1 row(s) affected)

-----------------------------------
The ATAN of 197.1099392 is: 1.56572

(1 row(s) affected)
``````

## Examples: Azure Synapse Analytics and Analytics Platform System (PDW)

This example takes a float expression and returns the arctangent of the specified angle.

``````SELECT ATAN(45.87) AS atanCalc1,
ATAN(-181.01) AS atanCalc2,
ATAN(0) AS atanCalc3,
ATAN(0.1472738) AS atanCalc4,
ATAN(197.1099392) AS atanCalc5;
``````

Here is the result set.

``````atanCalc1  atanCalc2  atanCalc3  atanCalc4  atanCalc5
---------  ---------  ---------  ---------  ---------
1.55       -1.57       0.00       0.15       1.57
``````