PRODUCT (The GNU Fortran Compiler)

### 8.229 `PRODUCT` — Product of array elements ¶

Synopsis:

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

Description:

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

Class:

  Transformational function

Arguments:

  ARRAY | Shall be an array of type `INTEGER`, `REAL`, `COMPLEX` or `UNSIGNED`.
  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 ARRAY.
  MASK | (Optional) shall be of type `LOGICAL` and either be a scalar or an array of the same shape as ARRAY.

Return value:

  The result is of the same type as ARRAY.

  If DIM is absent, a scalar with the product of all elements in ARRAY is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned.

Example:

      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

Standard:

  Fortran 90 and later, extension for `UNSIGNED` (see Unsigned integers)

See also:

  `SUM` — Sum of array elements