CODEWITHSUNDEEP
fortranintel-fortran
Looper
Looper

Reputation: 364

Free-dimensional array as input in subroutine

I am trying to write a subroutine that can take as input a one-dimensional array OR a two-dimensional array. How can I declare that the input of the subroutine can be either be a vector or a matrix?

If I do this:

SUBROUTINE TEST1(x)
   REAL, INTENT(IN) :: x(:)
   <do something>
END SUBROUTINE TEST1

I clearly cannot pass a matrix as an input in the subroutine. A non-elegant solution could be to pass the matrix in vectorized form and then re-arrange it in matrix form inside the subroutine (I would need a couple of extra inputs, of course). Is there a better way of doing this?

Upvotes: 1

Views: 337

Answers (2)

Holmz
Holmz

Reputation: 724

With Intel you can also use MAP/UNION, so you can pass the 1d as a one 1d, and also pass the 2D as it's MAP/UNION 1D version.

You may want to use RESHAPE, but usually it is not needed, depending on what you are doing.

Your comment of "clearly cannot pass in a matrix" seems counter to what I know. If it is 2D, and always 2D, then there is no issue whatsoever. You can pass any rank in.

Upvotes: 0

agentp
agentp

Reputation: 6989

creating a generic interface seems a pretty clean way to do it. (per comment, but I though worth writing up )

 module gen
 interface test1
 module procedure t1,t2
 end interface
 contains 
 subroutine t1(y)
 real y(:)
 write(*,*)'shape is',shape(y)
 y=2*y
 end subroutine
 subroutine t2(y)
 real y(:,:)
 write(*,*)'shape is',shape(y)
 y=2*y
 end subroutine
 end module

 use gen
 real m(4),n(3,3)
 m=4 
 n=3
 call test1(m)
 call test1(n)
 end

Upvotes: 1

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