1 /* 2 Full multigrid using either additive or multiplicative V or W cycle 3 */ 4 #include "src/ksp/pc/impls/mg/mgimpl.h" 5 6 EXTERN PetscErrorCode MGMCycle_Private(MG *,PetscTruth*); 7 8 /* 9 MGFCycle_Private - Given an MG structure created with MGCreate() runs 10 full multigrid. 11 12 Iput Parameters: 13 . mg - structure created with MGCreate(). 14 15 Note: This may not be what others call full multigrid. What we 16 do is restrict the rhs to all levels, then starting 17 on the coarsest level work our way up generating 18 initial guess for the next level. This provides an 19 improved preconditioner but not a great improvement. 20 */ 21 #undef __FUNCT__ 22 #define __FUNCT__ "MGFCycle_Private" 23 PetscErrorCode MGFCycle_Private(MG *mg) 24 { 25 int i,l = mg[0]->levels,ierr; 26 PetscScalar zero = 0.0; 27 28 PetscFunctionBegin; 29 /* restrict the RHS through all levels to coarsest. */ 30 for (i=l-1; i>0; i--){ 31 ierr = MatRestrict(mg[i]->restrct,mg[i]->b,mg[i-1]->b);CHKERRQ(ierr); 32 } 33 34 /* work our way up through the levels */ 35 ierr = VecSet(&zero,mg[0]->x);CHKERRQ(ierr); 36 for (i=0; i<l-1; i++) { 37 ierr = MGMCycle_Private(&mg[i],PETSC_NULL);CHKERRQ(ierr); 38 ierr = MatInterpolate(mg[i+1]->interpolate,mg[i]->x,mg[i+1]->x);CHKERRQ(ierr); 39 } 40 ierr = MGMCycle_Private(&mg[l-1],PETSC_NULL);CHKERRQ(ierr); 41 PetscFunctionReturn(0); 42 } 43 44 /* 45 MGKCycle_Private - Given an MG structure created with MGCreate() runs 46 full Kascade MG solve. 47 48 Iput Parameters: 49 . mg - structure created with MGCreate(). 50 51 Note: This may not be what others call Kascadic MG. 52 */ 53 #undef __FUNCT__ 54 #define __FUNCT__ "MGKCycle_Private" 55 PetscErrorCode MGKCycle_Private(MG *mg) 56 { 57 int i,l = mg[0]->levels,ierr; 58 PetscScalar zero = 0.0; 59 60 PetscFunctionBegin; 61 /* restrict the RHS through all levels to coarsest. */ 62 for (i=l-1; i>0; i--){ 63 ierr = MatRestrict(mg[i]->restrct,mg[i]->b,mg[i-1]->b);CHKERRQ(ierr); 64 } 65 66 /* work our way up through the levels */ 67 ierr = VecSet(&zero,mg[0]->x);CHKERRQ(ierr); 68 for (i=0; i<l-1; i++) { 69 if (mg[i]->eventsolve) {ierr = PetscLogEventBegin(mg[i]->eventsolve,0,0,0,0);CHKERRQ(ierr);} 70 ierr = KSPSolve(mg[i]->smoothd,mg[i]->b,mg[i]->x);CHKERRQ(ierr); 71 if (mg[i]->eventsolve) {ierr = PetscLogEventEnd(mg[i]->eventsolve,0,0,0,0);CHKERRQ(ierr);} 72 ierr = MatInterpolate(mg[i+1]->interpolate,mg[i]->x,mg[i+1]->x);CHKERRQ(ierr); 73 } 74 if (mg[l-1]->eventsolve) {ierr = PetscLogEventBegin(mg[l-1]->eventsolve,0,0,0,0);CHKERRQ(ierr);} 75 ierr = KSPSolve(mg[l-1]->smoothd,mg[l-1]->b,mg[l-1]->x);CHKERRQ(ierr); 76 if (mg[l-1]->eventsolve) {ierr = PetscLogEventEnd(mg[l-1]->eventsolve,0,0,0,0);CHKERRQ(ierr);} 77 78 PetscFunctionReturn(0); 79 } 80 81 82