Vector subscripts

A vector subscript is an integer array expression of rank one, designating a sequence of subscripts that correspond to the values of the elements of the expression.

A vector subscript can be a real array expression of rank one in XL Fortran.

The sequence does not have to be in order, and may contain duplicate values:

INTEGER A(10), B(3), C(3)
PRINT *, A( (/ 10,9,8 /) ) ! Last 3 elements in reverse order
B = A( (/ 1,2,2 /) )       ! B(1) = A(1), B(2) = A(2), B(3) = A(2) also
END

If a vector subscript has more than one element with the same value, an array section with that vector subscript cannot appear in any of the situations mentioned in Syntactic contexts of definition or undefinition of variables.

Notes:

An array section used as an internal file must not have a vector subscript.
If you pass an array section with a vector subscript as an actual argument, the associated dummy argument must not be defined or redefined.
An array section with a vector subscript must not be the target in a pointer assignment statement.
In XL Fortran, a nonzero-sized array section containing a vector subscript is considered noncontiguous. For details, see Contiguity.

! We can use the whole array VECTOR as a vector subscript for A and B
INTEGER, DIMENSION(3) :: VECTOR= (/ 1,3,2 /), A, B
INTEGER, DIMENSION(4) :: C = (/ 1,2,4,8 /)
A(VECTOR) = B            ! A(1) = B(1), A(3) = B(2), A(2) = B(3)
A = B( (/ 3,2,1 /) )     ! A(1) = B(3), A(2) = B(2), A(3) = B(1)
PRINT *, C(VECTOR(1:2))  ! Prints C(1), C(3)
END