..
  Copyright 1988-2022 Free Software Foundation, Inc.
  This is part of the GCC manual.
  For copying conditions, see the copyright.rst file.

.. _tanh:

.. index:: TANH

.. index:: DTANH

.. index:: hyperbolic tangent

.. index:: hyperbolic function, tangent

.. index:: tangent, hyperbolic

TANH --- Hyperbolic tangent function
*************************************

.. function:: TANH(X)

  ``TANH(X)`` computes the hyperbolic tangent of :samp:`{X}`.

  :param X:
    The type shall be ``REAL`` or ``COMPLEX``.

  :return:
    The return value has same type and kind as :samp:`{X}`. If :samp:`{X}` is
    complex, the imaginary part of the result is in radians. If :samp:`{X}`
    is ``REAL``, the return value lies in the range
    - 1 \leq tanh(x) \leq 1 .

  Standard:
    Fortran 77 and later, for a complex argument Fortran 2008 or later

  Class:
    Elemental function

  Syntax:
    .. code-block:: fortran

      X = TANH(X)

  Example:
    .. code-block:: fortran

      program test_tanh
        real(8) :: x = 2.1_8
        x = tanh(x)
      end program test_tanh

  Specific names:
    .. list-table::
       :header-rows: 1

       * - Name
         - Argument
         - Return type
         - Standard

       * - ``TANH(X)``
         - ``REAL(4) X``
         - ``REAL(4)``
         - Fortran 77 and later
       * - ``DTANH(X)``
         - ``REAL(8) X``
         - ``REAL(8)``
         - Fortran 77 and later

  See also:
    :ref:`ATANH`