All before using fortan code, did you have a look to the "vectorization" in order to avoid loops (that drastically decrease speed) and to increase speedup consequently ?
Just an advice Paul -----Message d'origine----- De : users [mailto:[email protected]] De la part de Pierre Vuillemin Envoyé : mercredi 5 février 2014 09:56 À : [email protected] Objet : [Scilab-users] Interfacing fortran code with scilab Hello all, I am currently learning fortran in order to speed up some part o my code and I would like to interface it with Scilab. To make some tests, I have used this fortran code : subroutine matmul(C,A,B,m,n,p) integer ::m,n,p,i,j,k real(kind=8),dimension(m,n),intent(in)::A real(kind=8),dimension(n,p),intent(in)::B real(kind=8),dimension(m,p),intent(out)::C real(kind=8):: temp C = 0 do j =1,p do k=1,n temp = B(k,j) do i=1,m C(i,j)=C(i,j) + A(i,k)*temp end do end do end do end subroutine matmul which performs a matrix multiplication. Then I have used 'ilib_for_link' to create the link. It works but I have some questions : - I did the same thing in Python with f2py and the code is seemingly faster in python, I was wondering why ? (the precision is the same) - If I change the 'kind = 8' to 'kind = 4' in the fortran code, the function returns a result which completely wrong. I expected it to be wrong, but not that much : for instance, with A = 10 and B = 20, the call to the fortran function gives me '6.36D-314' What is the reason? (My comprehension of how fortran types work with the kind parameter is still limited, I know that kind=8 and kind=4 is not a very portable expression though) - If I replace real(kind=8),dimension(m,p),intent(out)::C by real(kind=8),dimension(:,:),intent(out)::C I get a segfault in Scilab or it just closes. I was wondering why ? (I thought it was something valid since gfortran still compiles) - Is it possible to keep the upper case in the name of fortran functions when linked to scilab ? (At the beginning, my function was called 'matMul' and it took me some time to figure out what the error message 'matMul is not an entry point' meant) Best regards, Pierre Vuillemin _______________________________________________ users mailing list [email protected] https://urldefense.proofpoint.com/v1/url?u=http://lists.scilab.org/mailman/listinfo/users&k=b2vlTQszY8VIpYRvaG%2By2A%3D%3D%0A&r=SzPQe21KEY%2BPdUhJge5w%2FdtbtLgIXw5YTsnbzx%2F7JYE%3D%0A&m=ULVia0lWcxnisV%2BYAJ894mfD5PBI7UEZDeqeSqE9PQw%3D%0A&s=4501ea13ac011e234cb1dd1cdf1810c4388736b832cf43301a84c41f80b767f5 -------------------------------------------------------------------------------- Le présent mail et ses pièces jointes sont confidentiels et destinés à la personne ou aux personnes visée(s) ci-dessus. Si vous avez reçu cet e-mail par erreur, veuillez contacter immédiatement l'expéditeur et effacer le message de votre système. Toute divulgation, copie ou distribution de cet e-mail est strictement interdite. This email and any files transmitted with it are confidential and intended solely for the use of the individual or entity to whom they are addressed. If you have received this email in error, please contact the sender and delete the email from your system. If you are not the named addressee you should not disseminate, distribute or copy this email. _______________________________________________ users mailing list [email protected] http://lists.scilab.org/mailman/listinfo/users
