1 #include <petsc-private/snesimpl.h> /*I "petscsnes.h" I*/ 2 #include <petscdm.h> 3 4 #undef __FUNCT__ 5 #define __FUNCT__ "MatMultASPIN" 6 PetscErrorCode MatMultASPIN(Mat m,Vec X,Vec Y) 7 { 8 PetscErrorCode ierr; 9 void *ctx; 10 SNES snes; 11 PetscInt n,i; 12 VecScatter *oscatter; 13 SNES *subsnes; 14 PetscBool match; 15 MPI_Comm comm; 16 KSP ksp; 17 Vec *x,*b; 18 SNES npc; 19 20 PetscFunctionBegin; 21 ierr = MatShellGetContext(m,&ctx);CHKERRQ(ierr); 22 snes = (SNES)ctx; 23 ierr = SNESGetPC(snes,&npc);CHKERRQ(ierr); 24 ierr = PetscObjectTypeCompare((PetscObject)npc,SNESNASM,&match);CHKERRQ(ierr); 25 if (!match) { 26 ierr = PetscObjectGetComm((PetscObject)snes,&comm); 27 SETERRQ(comm,PETSC_ERR_ARG_WRONGSTATE,"MatMultASPIN requires that the nonlinear preconditioner be Nonlinear additive Schwarz"); 28 } 29 ierr = SNESNASMGetSubdomains(npc,&n,&subsnes,NULL,&oscatter,NULL);CHKERRQ(ierr); 30 ierr = SNESNASMGetSubdomainVecs(npc,&n,&x,&b,NULL,NULL);CHKERRQ(ierr); 31 ierr = MatMult(npc->jacobian_pre,X,Y);CHKERRQ(ierr); 32 for (i=0;i<n;i++) { 33 ierr = VecScatterBegin(oscatter[i],Y,b[i],INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr); 34 ierr = VecScatterEnd(oscatter[i],Y,b[i],INSERT_VALUES,SCATTER_FORWARD);CHKERRQ(ierr); 35 } 36 ierr = MPI_Barrier(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr); 37 for (i=0;i<n;i++) { 38 ierr = VecSet(x[i],0);CHKERRQ(ierr); 39 ierr = SNESGetKSP(subsnes[i],&ksp);CHKERRQ(ierr); 40 ierr = KSPSolve(ksp,b[i],x[i]);CHKERRQ(ierr); 41 } 42 ierr = VecSet(Y,0);CHKERRQ(ierr); 43 ierr = MPI_Barrier(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr); 44 for (i=0;i<n;i++) { 45 ierr = VecScatterBegin(oscatter[i],x[i],Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr); 46 ierr = VecScatterEnd(oscatter[i],x[i],Y,ADD_VALUES,SCATTER_REVERSE);CHKERRQ(ierr); 47 } 48 49 ierr = MPI_Barrier(PetscObjectComm((PetscObject)snes));CHKERRQ(ierr); 50 51 PetscFunctionReturn(0); 52 } 53 54 EXTERN_C_BEGIN 55 #undef __FUNCT__ 56 #define __FUNCT__ "SNESCreate_ASPIN" 57 /* -------------------------------------------------------------------------- */ 58 /*MC 59 SNESASPIN - Helper SNES type for Additive-Schwarz Preconditioned Inexact Newton 60 61 Options Database: 62 + -npc_snes_ - options prefix of the nonlinear subdomain solver (must be of type NASM) 63 . -npc_sub_snes_ - options prefix of the subdomain nonlinear solves 64 . -npc_sub_ksp_ - options prefix of the subdomain Krylov solver 65 - -npc_sub_pc_ - options prefix of the subdomain preconditioner 66 67 Notes: This routine sets up an instance of NETWONLS with nonlinear left preconditioning. It differs from other 68 similar functionality in SNES as it creates a linear shell matrix that corresponds to the product: 69 70 \sum_{i=0}^{N_b}J_b({X^b_{converged}})^{-1}J(X + \sum_{i=0}^{N_b}(X^b_{converged} - X^b)) 71 72 which is the ASPIN preconditioned matrix. Similar solvers may be constructed by having matrix-free differencing of 73 nonlinear solves per linear iteration, but this is far more efficient when subdomain sparse-direct preconditioner 74 factorizations are reused on each application of J_b^{-1}. 75 76 Level: intermediate 77 78 .seealso: SNESCreate(), SNES, SNESSetType(), SNESNEWTONLS, SNESNASM, SNESGetPC(), SNESGetPCSide() 79 80 M*/ 81 PetscErrorCode SNESCreate_ASPIN(SNES snes) 82 { 83 PetscErrorCode ierr; 84 SNES npc; 85 KSP ksp; 86 PC pc; 87 Mat aspinmat; 88 MPI_Comm comm; 89 Vec F; 90 PetscInt n; 91 92 PetscFunctionBegin; 93 /* set up the solver */ 94 ierr = SNESSetType(snes,SNESNEWTONLS);CHKERRQ(ierr); 95 ierr = SNESSetPCSide(snes,PC_LEFT);CHKERRQ(ierr); 96 ierr = SNESGetPC(snes,&npc);CHKERRQ(ierr); 97 ierr = SNESSetType(npc,SNESNASM);CHKERRQ(ierr); 98 ierr = SNESNASMSetComputeFinalJacobian(npc,PETSC_TRUE);CHKERRQ(ierr); 99 ierr = SNESGetKSP(snes,&ksp);CHKERRQ(ierr); 100 ierr = KSPGetPC(ksp,&pc);CHKERRQ(ierr); 101 ierr = PCSetType(pc,PCNONE);CHKERRQ(ierr); 102 ierr = PetscObjectGetComm((PetscObject)snes,&comm); 103 104 /* set up the shell matrix */ 105 ierr = SNESGetFunction(snes,&F,NULL,NULL);CHKERRQ(ierr); 106 ierr = VecGetLocalSize(F,&n);CHKERRQ(ierr); 107 ierr = MatCreateShell(comm,n,n,PETSC_DECIDE,PETSC_DECIDE,snes,&aspinmat);CHKERRQ(ierr); 108 ierr = MatSetType(aspinmat,MATSHELL);CHKERRQ(ierr); 109 ierr = MatShellSetOperation(aspinmat,MATOP_MULT,(void(*)(void))MatMultASPIN);CHKERRQ(ierr); 110 111 ierr = SNESSetJacobian(snes,aspinmat,NULL,NULL,NULL);CHKERRQ(ierr); 112 ierr = MatDestroy(&aspinmat);CHKERRQ(ierr); 113 114 PetscFunctionReturn(0); 115 } 116 EXTERN_C_END 117