parallel processing - Scattered indices in MPI -

i'm trying divide array between processors such each 1 takes points different parts in array. example, if

a = {1, 2, 3, 4, 5, 6, 7, 8} 

and i'm using 2 processors, want p₁ handle {1, 3, 5, 7}, , p₂ handle {2, 4, 6, 8}.

when scaling large numbers of points (millions) , processors (128), tricky. in previous versions of function, gave p₁ first chunk of points, p₂ next chunk, , on (which easy mpi_gatherv).

is there way use mpi_gatherv make work, or way use mpi_send , mpi_receive achieve it? trouble mpi_gatherv while can specify indices processors send to, still puts of p₁ before p₂ before p₃ etc.