rank values passed in subroutines

Question

I am having some issues with using multi-dimensional array in some fortran code I am writing.

Basically, I define a 2-dimensional array, which is passed to membrane, then have to pass a 1-dimensional version of it to set.

Case (1)
  Call membrane ("Set", scv(i,:), sty)

Here is the routine that takes the 1-d array.

Subroutine membrane (tsk, scv, sty)
Implicit None
Character (Len=*), Intent (In) :: tsk
Logical, Intent (In), Optional :: scv(:,:)
Character (Len=*), Intent (In), Optional :: sty

Select Case (tsk)

Case ("Set")
  Call set (tsk, scv(1,:), sty) 

...

Here is my set subroutine

Subroutine set (tsk, scv, sty)

Implicit None
Character (Len=*), Intent (In) :: tsk
Logical, Intent (In), Optional :: scv(:)
Character (Len=*), Intent (In), Optional :: sty

I then get this error when I try to compile my code

sct/btun/membrane.f:185:35:

     Call membrane ("Set", scv(i,:), sty)
                               1
Error: Rank mismatch in argument 'scv' at (1) 
(rank-2 and rank-1)

Answer 1

You are calling the routine membrane using a one-dimensional slice of scv. Since that subroutine is expecting a two-dimensional array:

Logical, Intent (In), Optional :: scv(:,:)

You get the error. I am not quite sure what you are trying to achieve, but since you are accessing the first column of the array in membrane (hard-coded), I would change the dummy argument scv to be one-dimensional in membrane:

Subroutine membrane (tsk, scv, sty)
...
Logical, Intent (In), Optional :: scv(:)
...

Select Case (tsk)

Case ("Set")
  Call set (tsk, scv(:), sty) 
...

Note that that now the complete array is passed to set.

Alternatively, pass the complete 2D array to membrane along with the counter i, and pass the i-th row to set.

Answer 2

"then have to pass a 1-dimensional version of it to set"

but the subroutine expects a 2D array because of

Logical, Intent (In), Optional :: scv(:,:)

Either fix the declaration or you must pass a 2D array.