SQL Server ATAN() Function

 The ATAN() function in SQL Server returns the arctangent of a specified number. The arctangent is the inverse of the tangent function and is used to compute the angle (in radians) whose tangent is the specified number.

Syntax:

ATAN(float_expression)

Parameter:

• float_expression: A numeric expression (of type float) for which you want to calculate the arctangent.

Returns:

• The function returns a value in radians in the range -π/2 to π/2.

Example Usage:

1. Basic Example:

   SELECT ATAN(1) AS Arctangent;
   

   Output:

   • The arctangent of 1 is approximately 0.785398 radians (which equals π/4).

2. Using with a column: Assume you have a table named Angles with a column TangentValues.

   SELECT TangentValues, ATAN(TangentValues) AS Arctangent
   FROM Angles;
   

3. Convert radians to degrees: To convert the result from radians to degrees:

   SELECT ATAN(1) * (180.0 / PI()) AS ArctangentInDegrees;
   

   Output:

   • The result is approximately 45 degrees.

Notes:

• If you need to compute the arctangent for two coordinates $y$ and $x$, you can use the ATAN2(y, x) function.
• The input to the function must be numeric. If a non-numeric value or NULL is passed, the function may return an error or NULL.