Add a block-structured distributed operator that presents itself to Krylov
solvers and preconditioners as a single ordinary distributed matrix (the
PSBLAS analogue of PETSc MATNEST), targeting saddle-point systems
M = [[A, B^T], [B, 0]] with possibly rectangular sub-blocks.
Library (base/modules):
- psb_desc_nest_mod, psb_d_nest_mat_mod: grid of per-field descriptors and
per-block sparse storage.
- psb_d_nest_base_mat_mod: psb_d_nest_base_mat, the operator extending
psb_d_base_sparse_mat (local csmv, free, field-split hooks for a future
block preconditioner).
- psb_cd_nest_tools_mod / psb_d_nest_tools_mod: composed global descriptor
with union halo (psb_cd_nest_compose) and rectangular local block builder
(psb_d_nest_rect_block), plus the per-block assembly wrappers.
- psb_d_nest_builder_mod: psb_d_nest_matrix, the user frontend with the
init/ins/asb/free pattern hiding all descriptor/halo/compose/setup
boilerplate.
- psb_d_nest_mod: umbrella module (use psb_d_nest_mod).
Remove the earlier bespoke per-block prototype (comm/psblas/vect modules and
the pde_nest_psblas test) superseded by the single MATNEST design.
Tests (test/nested): glob (square operator vs monolithic CSR oracle), rect
(genuinely rectangular blocks), cg (low-level path, ill-conditioned SPD
red-black Laplacian solved with standard CG), builder (same solve via the
utility), plus a README describing the design and usage. All pass serially
and in parallel, with results invariant to the process count.
Build hooks updated (autotools Makefiles + CMakeLists); the nested tests are
relocated out of test/pdegen into test/nested.
Author: Simone Staccone (Stack-1)
Stack-1
jalmerol
sfilippone
Salvatore Filippone
Fabio Durastante