What's the best way to do this?

alexismor · ‎09-19-2005

Hi everyone,

I'm slowly getting better at Fortran, in no small part to your numerous contributions. I was wondering if someone could tell me the best way to do this:

dim=size(H(1,: )) !it's a square matrix
k=0
forall(i=1:dim,j=1:dim,H(i,j).ne.0)
k=k+1
row(k)=i
col(k)=j
val(k)=H(i,j)
end forall

I know that this code is illegal, but it represents what I'd like to do (which is fill 3 arrays with the row, column and value of the non-zero elements of H).

Thanks!

Message Edited by alexismor on 09-18-2005 09:30 PM

Message Edited by alexismor on 09-18-2005 09:31 PM

Jugoslav_Dujic · ‎09-19-2005

What's wrong with a plain vanilla do-loop?

DO j=1,n
   DO i=1,n
      IF (H(i,j).NE.0) THEN
         k = k+1
         row(k) = i
         col(k) = j
         val(k) = H(i,j)
      END IF
   END DO
END DO

Jugoslav

alexismor · ‎09-19-2005

Hi Jugoslav,

I guess nothing is wrong with it. I'm just trying to use the intrinsic functions as much as possible because it just seems more elegant :) (and faster since at some point I'll be running my code on a cluster).

Cheers,

Alexis