these question from "Introduction to Parallel Computing, Second Edition By Ananth Grama, Anshul Gupta, George Karypis, Vipin Kumar" chapter 6

:please dont use copy and paste from another answer:

6.8 Consider Dijkstra's single-source shortest-path algorithm described in Section 6.6.9. Describe why a column-wise distribution is preferable to a row-wise distribution of the weighted adjacency matrix.

6.9 Show how the two-dimensional matrix-vector multiplication program (Program 6.8) needs to be changed so that it will work correctly for a matrix of size n x m on a q x r process grid.