Newsgroups: comp.parallel.mpi From: Yon Han CHONG Subject: Re: MPI-2: MPI_TYPE_CREATE_SUBARRAY (Fortran binding issue) Organization: Cranfield University Date: Wed, 11 Mar 1998 10:05:08 +0000 Mime-Version: 1.0 Content-Type: text/plain; charset=EUC-KR Content-Transfer-Encoding: 7bit Message-ID: <350661D4.BF4DAE03@cranfield.ac.uk> Rajeev Thakur wrote: > > In article <35056083.B5F717B2@cranfield.ac.uk>, > Yon Han CHONG wrote: > >In MPI-2 it is defined that the begining of subarrary index should be > >a positive numbers. In C, this does make sense. You do not want to go > >over the boundary. In Fortran, this is restrictive because sometimes > >it is more convient to define an array as following: > > > > integer, parameter :: N=5 > > real, dimension(-1:N+2) :: a_local > > > >"a_local" cannot be a subarray since the index start from a negative > >number. > > This is one of the reasons why MPI_Type_create_subarray > uses 0-based indexing for the subarray index. It is natural in C for > one. In Fortran, since an array could be defined in many ways, for > example, 1 to 200 or -100 to 100, we need to select one > way to specify the subarray. We chose 0-based. So if your Fortran > array is (-1:N+2), and the subarray you want out of it is (5:10), > specify it as (6:11) to MPI_Type_create_subarray. > > Rajeev Yes, but if my array is (-1:N+2) and I would like my subarray to be (-1:3) then how can I do it? Do I specify (0:0) to MPI_Type_create_subarray? -- ---------------------------------------------------------------------- Yon Han Chong | Flow Control and Prediction Group | Tel: + 44 1234 750 111 ext. 5420 Cranfield College of Aeronautics | E-mail: Y.H.Chong@cranfield.ac.uk Cranfield University | Fax: + 44 1234 752 149 United Kingdom | Mobile: + 44 958 381 395 ----------------------------------------------------------------------