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

.. _exp:

EXP --- Exponential function 
*****************************

.. index:: EXP

.. index:: DEXP

.. index:: CEXP

.. index:: ZEXP

.. index:: CDEXP

.. index:: exponential function

.. index:: logarithm function, inverse

.. function:: EXP(X)

  ``EXP(X)`` computes the base e exponential of :samp:`{X}`.

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

  :return:
    The return value has same type and kind as :samp:`{X}`.

  :samp:`{Standard}:`
    Fortran 77 and later, has overloads that are GNU extensions

  :samp:`{Class}:`
    Elemental function

  :samp:`{Syntax}:`

  .. code-block:: fortran

    RESULT = EXP(X)

  :samp:`{Example}:`

    .. code-block:: fortran

      program test_exp
        real :: x = 1.0
        x = exp(x)
      end program test_exp

  :samp:`{Specific names}:`
    ============  ================  ==============  ====================
    Name          Argument          Return type     Standard
    ============  ================  ==============  ====================
    ``EXP(X)``    ``REAL(4) X``     ``REAL(4)``     Fortran 77 and later
    ``DEXP(X)``   ``REAL(8) X``     ``REAL(8)``     Fortran 77 and later
    ``CEXP(X)``   ``COMPLEX(4) X``  ``COMPLEX(4)``  Fortran 77 and later
    ``ZEXP(X)``   ``COMPLEX(8) X``  ``COMPLEX(8)``  GNU extension
    ``CDEXP(X)``  ``COMPLEX(8) X``  ``COMPLEX(8)``  GNU extension
    ============  ================  ==============  ====================