(j3.2006) Actual argument rank 2 array X(1, 4) associated with dummy rank 1 array - is that allowed ?

[Toon Moene]

I came upon a piece of code in our Weather Forecasting system that 
roughly did the following:

SUBROUTINE A(X, N)
REAL X(N, 4), Y(N)
...
CALL B(Y, N)
DO I = 1, N
    X(I,4) = Y
ENDDO
...
END
SUBROUTINE B(Z, N)
REAL Z(N)
...
DO I = 1, N
    Z(I) = ... some expression ...
ENDDO
END

This is of course correct, but probably overly so.  I thought it would 
be possible to code this as:

SUBROUTINE A(X, N)
REAL X(N, 4)
...
CALL B(X(1,4), N)
...
END
SUBROUTINE B(Z, N)
REAL Z(N)
...
DO I = 1, N
    Z(I) = ... some expression ...
ENDDO
END

i.e., without the auxiliary array Y and the copy loop.

Now the hard part is to find where the Standard (I'm looking at N1782) 
allows this.  The closest that I can find is 12.5.2.4 par. 14 where it 
says that for assumed-shape arrays the rank of actual and dummy should 
be the same (this almost implies that for non-assumed-shape arrays they 
don't have to - then, by virtue of the way arrays are laid out [16.5.3.2 
par 2, point 7] Z would correspond to the fourth column of X).

Is this reasoning correct ?

Thanks in advance.

Happy Holidays !

-- 
Toon Moene - e-mail: toon at moene.org - phone: +31 346 214290
Saturnushof 14, 3738 XG  Maartensdijk, The Netherlands
At home: http://moene.org/~toon/
Progress of GNU Fortran: http://gcc.gnu.org/gcc-4.5/changes.html