Indexed datatypes

Indexed Datatype Constructor

• This constructor replicates a datatype, taking blocks at fixed offsets.

     mpi_type_indexed (count, B, I, oldtype, 
                       newtype, ierr)

• The new datatype consists of:
  • count blocks,
  • the ith block is of length B[i] items of oldtype,
  • the offset of the start of the ith block is I[i] items of oldtype.
• If count=2, , and , then newtype is:

        {(double, 64),  (char,  72),
         (double, 80),  (char,  88),
         (double, 96),  (char, 104),
         (double,  0),  (char,   8)}