PnetCDF library: specific command question for f90

[Latham, Robert J.]

(Louis, I don't know why our mailing list auto-discarded your message,
so I'm sending it on your behalf )

Dear Parallel-NetCDF users/developers,

I’m Louis Monier, a young undergraduate from France who joined Zhiming
Kuang’s research group in Harvard university for 4 months (internship).
I’m working on the optimization of a  code (related to atmospheric
modelling) with the use of PnetCDF to speed up the output process. 

I’d have a specific question about a writing command of PnetCDF. 

Let’s say I have 4 different processors. Each one of them has a vector
(length = 4 for example) filled with random integers:
rank 0 : [0, 0, 23, 0]
rank 1: [42, 0, 0, 0]
rank 2: [0, 0, 0, 91]
rank 3: [0, 71, 0, 0]
(I don’t use a particular syntax of a programming langage here, just
try to be as clear as possible)

Here is my question: does a F90 writing PnetCDF command exist that
allows those 4 processors to write to the same location in the NetCDF
file while summing the vectors ? 

If you see my point here, I would end up with a NetCDF file with,
somewhere in the file (depend on my ’start’ variable): [42, 71, 23, 91]


To say a little bit more about my project, I want to write (using
PnetCDF) the positions of millions of particles into a NetCDF file.
However, each particle has its own ID. When I write the data for each
time step, I first have to sort them within each process and write them
to the precise location in the NetCDF file related to their ID.

Thank you to inform me on this subject. 

Best regards, 

Louis Monier