Geoffrey Irving <[email protected]> writes: > On Oct 7, 2013, at 12:11 PM, Geoffrey Irving <[email protected]> wrote: > >> Does src/ts/examples/tutorials/ex9.c support implicit methods for >> stiff problems? It doesn't explicitly create any linear solvers, but >> maybe these are created automatically if you pick the appropriate TS? >> That would presumably require derivative information though, which I >> don't see.
The example assembles a block-diagonal matrix based on a cell-centered characteristic decomposition for preconditioning. I don't recall if it was ever tested. Better to just use coloring (really easy and not very wasteful 1D problems). Here is an example of a shallow water dam-break using an implicit time integrator. ./ex9 -da_grid_x 100 -initial 0 -xmin -2 -xmax 2 -limit mc -physics shallow -bc_type outflow -ts_final_time 1 -ts_monitor_draw_solution -ts_type arkimex -ts_arkimex_fully_implicit -ts_adapt_type none -snes_converged_reason -ts_monitor -snes_fd_color -ts_max_snes_failures -1 Note that the problems in this example are non-stiff so implicit methods won't be more efficient.
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