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

.. index:: PRODUCT, array, product, array, multiply elements, array, conditionally multiply elements, multiply array elements

.. _product:

PRODUCT --- Product of array elements
*************************************

.. function:: PRODUCT(ARRAY, DIM, MASK)

  Multiplies the elements of :samp:`{ARRAY}` along dimension :samp:`{DIM}` if
  the corresponding element in :samp:`{MASK}` is ``TRUE``.

  :param ARRAY:
    Shall be an array of type ``INTEGER``,
    ``REAL`` or ``COMPLEX``.

  :param DIM:
    (Optional) shall be a scalar of type
    ``INTEGER`` with a value in the range from 1 to n, where n
    equals the rank of :samp:`{ARRAY}`.

  :param MASK:
    (Optional) shall be of type ``LOGICAL``
    and either be a scalar or an array of the same shape as :samp:`{ARRAY}`.

  :return:
    The result is of the same type as :samp:`{ARRAY}`.

  Standard:
    Fortran 90 and later

  Class:
    Transformational function

  Syntax:
    .. code-block:: fortran

      RESULT = PRODUCT(ARRAY[, MASK])
      RESULT = PRODUCT(ARRAY, DIM[, MASK])

  Example:
    .. code-block:: fortran

      PROGRAM test_product
        INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
        print *, PRODUCT(x)                    ! all elements, product = 120
        print *, PRODUCT(x, MASK=MOD(x, 2)==1) ! odd elements, product = 15
      END PROGRAM

  See also:
    :ref:`SUM`