Example of Vector type
Suppose in C, we have an array
- phi [ypoints+2] [xpoints+2]
- where we want to send rows and columns of elements from 1 : nxblock and 1 : nyblock
- in C, arrays are stored row major order (Fortran is column major)
MPI_Type_vector (xpoints, 1, ypoints+2, MPI_DOUBLE, &strided);
defines a type called strided which refers to the column of elements