An Unstructured Grid Example.
This example demonstrates how to solve a nonlinear system in parallel
with SNES for an unstructured mesh. The mesh and partitioning information
is read in an application defined ordering,which is later transformed
into another convenient ordering (called the local ordering). The local
ordering, apart from being efficient on cpu cycles and memory, allows
the use of the SPMD model of parallel programming. After partitioning
is done, scatters are created between local (sequential)and global
(distributed) vectors. Finally, we set up the nonlinear solver context
in the usual way as a structured grid (see
This example also illustrates the use of parallel matrix coloring.