FORALL (j=1:m, k=1:n) x(k,j) =index.html y(j,k)
FORALL (k=1:n) x(k,1:m) = y(1:m,k)
These statements both copy columns 1 through of array
into
rows 1 through
of array
. This is equivalent to the
standard Fortran 90 statement
x(1:n,1:m) =index.html TRANSPOSE(y(1:m,1:n))
FORALL (i=1:n, j=1:n) x(i,j) = 1.0 / REAL(i+j-1)
This FORALL sets array element to the value
for values of
and
between 1 and
.
In Fortran 90, the same operation can be performed by the statement
x(1:n,1:n) =index.html 1.0/REAL( SPREAD((/(i,i=1,n)/),DIM=2,NCOPIES=n) & + SPREAD((/(j,j=1,n)/),DIM=1,NCOPIES=n) - 1 ) Note that the FORALL statement does not imply the creation of temporary arrays and is much more readable.
FORALL (i=1:n, j=1:n, y(i,j).NE.0.0) x(i,j) =index.html 1.0 / y(i,j)
This statement takes the reciprocal of each nonzero element of
array and
assigns it to the corresponding element of array
.
Elements of
that are zero do not have their reciprocal taken, and no
assignments are made to the corresponding elements of
.
This is equivalent to the standard Fortran 90 statement
WHERE (y(1:n,1:n) .NE. 0.0) x(1:n,1:n) =index.html 1 / y(1:n,1:n) TYPE monarch INTEGER, POINTER :: p END TYPE monarch TYPE(monarch) :: a(n) INTEGER, TARGET :: b(n)
! Set up a butterfly pattern
FORALL (j=1:n) a(j)This FORALL statement sets the elements of array to point
to a permutation of the elements of
. When
and
,
then elements 1 through 8 of
point to elements 3, 4, 1, 2, 7, 8,
5, and 6 of
, respectively. This requires a DO loop or
other control flow in Fortran 90.
FORALL ( i=1:n ) x(indx(i)) =index.html x(i) This FORALL statement is equivalent to the Fortran 90 array assignment
x(indx(1:n)) =index.html x(1:n)
If contains a permutation of the integers from 1 to
,
then the final contents of
will be a permutation of the original
values.
If
contains repeated values, neither the behavior of the FORALL nor the array assignment are defined by their respective standards.
FORALL (i=2:4) x(i) =index.html x(i-1) + x(i) + x(i+1) If this statement is executed with
then after execution the new values of array will be
This has the same effect as the Fortran 90 statement
x(2:4) =index.html x(1:3) + x(2:4) + x(3:5) Note that it does not have the same effect as the Fortran 90 loop
DO i =index.html 2, 4
x(i) = x(i-1) + x(i) + x(i+1)
END DO
FORALL (i=1:n) a(i,i) = x(i)
This FORALL statement sets the elements of the main diagonal of
matrix to the elements of vector
. This cannot be done by
an array assignment in Fortran 90 unless EQUIVALENCE or WHERE is also used.
FORALL (i=1:4) a(i,ix(i)) =index.html x(i)
This FORALL statement sets one element in each row of
matrix to an element of vector
. The particular elements
in
are chosen by the integer vector
. If
and array represents the matrix
before execution of the FORALL, then
will represent
after its execution. This operation cannot be accomplished with a
single array assignment in Fortran 90.
FORALL (k=1:9) x(k) =index.html SUM(x(1:10:k))
This FORALL statement computes nine sums of subarrays of x. (SUM is allowed in a FORALL because Fortran 90
intrinsic functions are pure; see Section 
.) If before
the FORALL
then after the FORALL
This computation cannot be done by Fortran 90 array expressions alone.