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9.249 SUM — Sum of array elements

Description:
Adds the elements of ARRAY along dimension DIM if the corresponding element in MASK is TRUE.
Standard:
Fortran 95 and later
Class:
Transformational function
Syntax:

RESULT = SUM(ARRAY[, MASK])
RESULT = SUM(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 sum 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_sum
            INTEGER :: x(5) = (/ 1, 2, 3, 4 ,5 /)
            print *, SUM(x)                        ! all elements, sum = 15
            print *, SUM(x, MASK=MOD(x, 2)==1)     ! odd elements, sum = 9
          END PROGRAM

See also:
PRODUCT