Description:  Returns the sum of all the elements in an entire array or in a specified dimension of an array.  
Class:  Transformational function; Generic  
Arguments:  ARRAY  Must be an array of type integer, real, or complex.  
DIM (opt)  Must be a scalar integer with a value in the range 1 to n, where n is the rank of ARRAY.  
MASK  Must be of type logical and conformable with ARRAY.  
Results:  The result is an array or a scalar of the
same data type as ARRAY.
The result is scalar if DIM is omitted or ARRAY has rank one. The following rules apply if DIM is omitted:
The following rules apply if DIM is specified:

Examples
SUM ((/2, 3, 4/)) returns the value 9 (sum of 2 + 3 + 4). SUM ((/2, 3, 4/), DIM=1) returns the same result.
SUM (B, MASK=B .LT. 0.0) returns the arithmetic sum of the negative elements of B.
C is the array
[ 1 2 3 ] [ 4 5 6 ].
SUM (C, DIM=1) returns the value (5, 7, 9), which is the sum of all elements in each column. 5 is the sum of 1 + 4 in column 1. 7 is the sum of 2 + 5 in column 2, and so forth.
SUM (C, DIM=2) returns the value (6, 15), which is the sum of all elements in each row. 6 is the sum of 1 + 2 + 3 in row 1. 15 is the sum of 4 + 5 + 6 in row 2.