..
  Copyright 1988-2021 Free Software Foundation, Inc.
  This is part of the GCC manual.
  For copying conditions, see the GPL license file

.. _atand:

ATAND --- Arctangent function, degrees
**************************************

.. index:: ATAND

.. index:: DATAND

.. index:: trigonometric function, tangent, inverse, degrees

.. index:: tangent, inverse, degrees

.. function:: ATAND(X)

  ``ATAND(X)`` computes the arctangent of :samp:`{X}` in degrees (inverse of
  TAND).

  :param X:
    The type shall be ``REAL`` or ``COMPLEX`` ;
    if :samp:`{Y}` is present, :samp:`{X}` shall be REAL.

  :param Y:
    The type and kind type parameter shall be the same as :samp:`{X}`.

  :return:
    The return value is of the same type and kind as :samp:`{X}`.
    If :samp:`{Y}` is present, the result is identical to ``ATAND2(Y,X)``.
    Otherwise, it is the arcus tangent of :samp:`{X}`, where the real part of
    the result is in degrees and lies in the range
    -90 \leq \Re \atand(x) \leq 90.

  :samp:`{Standard}:`
    GNU extension, enabled with :option:`-fdec-math`.

  :samp:`{Class}:`
    Elemental function

  :samp:`{Syntax}:`

  .. code-block:: fortran

    RESULT = ATAND(X)
    RESULT = ATAND(Y, X)

  :samp:`{Example}:`

    .. code-block:: fortran

      program test_atand
        real(8) :: x = 2.866_8
        x = atand(x)
      end program test_atand

  :samp:`{Specific names}:`
    =============  =============  ===========  =============
    Name           Argument       Return type  Standard
    =============  =============  ===========  =============
    ``ATAND(X)``   ``REAL(4) X``  ``REAL(4)``  GNU extension
    ``DATAND(X)``  ``REAL(8) X``  ``REAL(8)``  GNU extension
    =============  =============  ===========  =============

  :samp:`{See also}:`
    Inverse function: 
    TAND 
    Radians function: 
    ATAN