Kenneth_Smith
Joined: 18 May 2012
Posts: 726
Location: Hamilton, Lanarkshire, Scotland.
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 Posted: Wed Sep 20, 2023 12:11 pm Post subject: Array argument for a statement function |
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I am trying very hard to break the habit of using nested do loops for everything, i.e. use array operations where possible.
In the following code, I think I am breaking the rules of Fortran, but FTN95 does not report any ERROR or WARNING.
What I see here is FTN95 accepting an array argument for a one line statement function, which I think is not allowed?
Is my understanding correct (a bug) or am I missing something in my understanding?
| Code: | program p2
implicit none
integer, parameter :: n = 4
real*8 :: x(n) = 0, y(n) = 0, z(n,n) = 0
integer i,j
real*8 f, a, b
!Statement function to define a function f of two scalars x and y.
f(a,b) = a + b
x = [1,2,3,4]
y = [1,2,3,4]
do i = 1, n
z(:,i) = f(x(:), y(i)) ! Should FTN95 not generate a fatal ERROR here?
end do
print*, 'Using array operation to eliminate one do loop and a statement function'
do i = 1, n
print*, (z(i,j),j = 1,n)
end do
print*
! This is allowed because f2 is elemental
do i = 1, n
z(:,i) = f2(x(:), y(i))
end do
print*, 'Using array operation to eliminate one do loop using elemental function'
do i = 1, n
print*, (z(i,j),j = 1,n)
end do
contains
real*8 elemental function f2(c,d)
real*8, intent(in) :: c, d
f2 = c+d
end function f2
end program p2 |
i.e. Is the assigment:
| Code: | | z(:,i) = f(x(:), y(i)) |
valid fortran in this context? |
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