Intel® Fortran Compiler

Developer Guide and Reference

ID 767251
Date 12/12/2025
Public
Document Table of Contents

ATANPI

Elemental Intrinsic Function (Generic): Produces the arctangent of x in half revolutions.

result = ATANPI (x)

or

result = ATANPI (y,x)

y

(Input; optional) If specified, it must be of type real and have the same KIND parameter as x.

x

(Input) Must be of type real. If y appears and has the value 0.0, x must not have the value 0.0.

Results

If y appears, the result is the same as the result of ATAN2PI (y, x). Otherwise, the result type and kind are the same as x and are expressed in half revolutions between ±0.5.

There are no specific names for this function.

Example

ATANPI (1.0) has the approximate value 0.25