Intel® Fortran Compiler

Developer Guide and Reference

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

ATAN2PI

Elemental Intrinsic Function (Generic): Produces an arctangent in half revolutions. The result is the principal value of the argument of the nonzero complex number (x, y).

result = ATAN2PI (y,x)

y

(Input) Must be of type real.

x

(Input) Must have the same type and kind parameters as y. If y has the value zero, x cannot have the value zero.

Results

The result type and kind are the same as x and are expressed in half revolutions. The value lies in the range -1.0 <= ATAN2PI (y, x) <= 1.0 . The value of the result is approximately equal to ATAN2 (y, x) divided by π (pi).

There are no specific names for this function.

Example

ATAN2PI (1.0, 1.0) has the approximate value 0.25.