HDF5 minimal example

hdf5.cpp

@@ -29,16 +29,12 @@ int main(int argc, char** argv)
   assert(H5Pclose(fapl) >= 0);
 
   // Let's create some sample data!
-  // Even MPI ranks have (100 + rank) integers worth of data, oddballs don't
-  // have any data.
-  std::vector<int> v(100 + comm_rank, comm_rank+10);
+  // MPI ranks have (100 + rank) integers worth of data
+  std::vector<int> v(100, comm_rank);
 
   // The extent of the dataspace in the file can be computed accordingly.
-  hsize_t size = 100 * (comm_size / 2 + comm_size % 2) +
-                 (comm_size - 1) / 2 * ((comm_size - 1) / 2 + 1);
-  printf("Size %d", size);
-
-  size = comm_size * 100 + (comm_size) * (comm_size - 1) / 2;
+  hsize_t size = 100*comm_size; //+ comm_size*(comm_size-1)/2 ;
+ 
   printf("Size %d", size);
 
   // Make a dataset!
@@ -62,14 +58,16 @@ int main(int argc, char** argv)
   offset =
       comm_rank / 2 * 100 + (comm_rank - 1) / 2 * ((comm_rank - 1) / 2 + 1);
 
-  offset = comm_rank*100+(comm_rank)*(comm_rank-1)/2;
+  offset = comm_rank*100; //+(comm_rank)*(comm_rank-1)/2;
 
   printf("offset %d of rank %d \n", offset, comm_rank);
   assert(H5Sselect_hyperslab(fspace, H5S_SELECT_SET, &offset, NULL, &one,
                              &blk) >= 0);
 
-  assert(H5Sselect_none(mspace) >= 0);
-  assert(H5Sselect_none(fspace) >= 0);
+  assert(H5Sselect_all(mspace) >= 0);
+  offset = comm_rank * 100;
+  assert(H5Sselect_hyperslab(fspace, H5S_SELECT_SET, &offset, NULL, &one,
+                                &blk) >= 0);
 
   assert(H5Dwrite(dset, H5T_NATIVE_INT, mspace, fspace, H5P_DEFAULT,
                   v.data()) >= 0);