ATAN scalar function

The ATAN function returns the arc tangent of the argument as an angle, expressed in radians. The ATAN and TAN functions are inverse operations.

Read syntax diagramSkip visual syntax diagramATAN( numeric-expression)

The schema is SYSIBM.

The argument must be an expression that returns the value of any built-in numeric data type that is not DECFLOAT. The value must be greater than or equal to -1 and less than or equal to 1. If the argument is not a double precision floating-point number, it is converted to one for processing by the function.

The result of the function is a double precision floating-point number.

The result can be null; if the argument is null, the result is the null value.

The result is greater than or equal to -π/2 and less than or equal to π/2.

Example: Assume that host variable ATANGENT is DECIMAL(10,9) with a value of 14.10141995. The following statement returns a double precision floating-point number with an approximate value of 1.50: 
   SELECT ATAN(:ATANGENT)
     FROM SYSIBM.SYSDUMMY1;