9.220 PRODUCT — Product of array elements

Description:

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

Standard:

Fortran 90 and later

Class:

Transformational function

Syntax:

RESULT = PRODUCT(ARRAY[, MASK])

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

Arguments:

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

See also:

SUM