c - Transpose matrix with MPI_Alltoallv

Question

I'd like to transpose a matrix b using MPI_Alltoallv and store it in bt.

Each process contain nlocal rows of b. For example:

Proc0: 0 | 10 | 20 | 30

Proc0: 1 | 11 | 21 | 31

Proc1: 100 | 110 | 120 | 130

Proc1: 101 | 111 | 121 | 131

I'd like bt being like:

Proc0: 0 | 1 | 100 | 101

Proc0: 10 | 11 | 110 | 111

Proc1: 20 | 21 | 120 | 121

Proc1: 30 | 31 | 130 | 131

The submatrices are stored in 2d arrays (b[0] contains the first row and b[1] the second row). I found the solution when each process contains only one row, but not when I have several. Any ideas ?

Answer 1

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