1f7765cecSBarry Smith #ifndef lint 2*f09e8eb9SSatish Balay static char vcid[] = "$Id: pcnull.c,v 1.9 1997/02/22 02:23:59 bsmith Exp balay $"; 3f7765cecSBarry Smith #endif 4f7765cecSBarry Smith /* 5b4fd4287SBarry Smith Routines to project vectors out of null spaces. 6f7765cecSBarry Smith */ 7f7765cecSBarry Smith 8f7765cecSBarry Smith #include "petsc.h" 970f55243SBarry Smith #include "src/pc/pcimpl.h" /*I "pc.h" I*/ 10f7765cecSBarry Smith #include <stdio.h> 11f5eb4b81SSatish Balay #include "src/sys/nreg.h" 12f7765cecSBarry Smith #include "sys.h" 13f7765cecSBarry Smith 14f7765cecSBarry Smith 155615d1e5SSatish Balay #undef __FUNC__ 165615d1e5SSatish Balay #define __FUNC__ "PCNullSpaceCreate" 17112a2221SBarry Smith /*@C 18b4fd4287SBarry Smith PCNullSpaceCreate - Creates a data-structure used to project vectors 19b4fd4287SBarry Smith out of null spaces. 20f7765cecSBarry Smith 21f7765cecSBarry Smith Input Parameters: 22b4fd4287SBarry Smith . comm - the MPI communicator associated with the object. 23b4fd4287SBarry Smith . has_cnst - if the null spaces contains the constant vector, PETSC_TRUE or PETSC_FALSE 24b4fd4287SBarry Smith . n - number of vectors (excluding constant vector) in null space 25b4fd4287SBarry Smith . vecs - the vectors that span the null space (excluding the constant vector) 26b4fd4287SBarry Smith . these vectors must be orthonormal 27f7765cecSBarry Smith 28f7765cecSBarry Smith Output Parameter: 29b4fd4287SBarry Smith . SP - the null space context 30f7765cecSBarry Smith 31f7765cecSBarry Smith 32b4fd4287SBarry Smith .keywords: PC, Null space 33f7765cecSBarry Smith @*/ 34b4fd4287SBarry Smith int PCNullSpaceCreate(MPI_Comm comm, int has_cnst, int n, Vec *vecs,PCNullSpace *SP) 35f7765cecSBarry Smith { 36b4fd4287SBarry Smith PCNullSpace sp; 37f7765cecSBarry Smith 38*f09e8eb9SSatish Balay PetscHeaderCreate(sp,_p_PCNullSpace,PCNULLSPACE_COOKIE,0,comm); 39b4fd4287SBarry Smith PLogObjectCreate(sp); 40*f09e8eb9SSatish Balay PLogObjectMemory(sp,sizeof(struct _p_PCNullSpace)); 41f7765cecSBarry Smith 42b4fd4287SBarry Smith sp->has_cnst = has_cnst; 43b4fd4287SBarry Smith sp->n = n; 44b4fd4287SBarry Smith sp->vecs = vecs; 45b4fd4287SBarry Smith 46b4fd4287SBarry Smith *SP = sp; 47f7765cecSBarry Smith return 0; 48f7765cecSBarry Smith } 49f7765cecSBarry Smith 505615d1e5SSatish Balay #undef __FUNC__ 515eea60f9SBarry Smith #define __FUNC__ "PCNullSpaceDestroy" /* ADIC Ignore */ 52f7765cecSBarry Smith /*@ 53b4fd4287SBarry Smith PCNullSpaceDestroy - Destroys a data-structure used to project vectors 54b4fd4287SBarry Smith out of null spaces. 55b4fd4287SBarry Smith 56b4fd4287SBarry Smith Input Parameter: 57b4fd4287SBarry Smith . SP - the null space context to be destroyed 58b4fd4287SBarry Smith 59b4fd4287SBarry Smith .keywords: PC, Null space 60b4fd4287SBarry Smith @*/ 61b4fd4287SBarry Smith int PCNullSpaceDestroy(PCNullSpace sp) 62b4fd4287SBarry Smith { 63b4fd4287SBarry Smith PLogObjectDestroy(sp); 64b4fd4287SBarry Smith PetscHeaderDestroy(sp); 65b4fd4287SBarry Smith return 0; 66b4fd4287SBarry Smith } 67b4fd4287SBarry Smith 685615d1e5SSatish Balay #undef __FUNC__ 695615d1e5SSatish Balay #define __FUNC__ "PCNullSpaceRemove" 70b4fd4287SBarry Smith /*@ 71b4fd4287SBarry Smith PCNullSpaceRemove - Removes all the components of a null space from a vector. 72f7765cecSBarry Smith 73f7765cecSBarry Smith Input Parameters: 74b4fd4287SBarry Smith . sp - the null space context 75b4fd4287SBarry Smith . vec - the vector you want the null space removed from 76f7765cecSBarry Smith 77f7765cecSBarry Smith 78b4fd4287SBarry Smith .keywords: PC, Null space 79f7765cecSBarry Smith @*/ 80b4fd4287SBarry Smith int PCNullSpaceRemove(PCNullSpace sp,Vec vec) 81f7765cecSBarry Smith { 82b4fd4287SBarry Smith Scalar sum; 83b4fd4287SBarry Smith int j, n = sp->n, N,ierr; 84f7765cecSBarry Smith 85b4fd4287SBarry Smith if (sp->has_cnst) { 86b4fd4287SBarry Smith ierr = VecSum(vec,&sum); CHKERRQ(ierr); 87b4fd4287SBarry Smith ierr = VecGetSize(vec,&N); CHKERRQ(ierr); 88b4fd4287SBarry Smith sum = -sum/N; 89b4fd4287SBarry Smith ierr = VecShift(&sum,vec); CHKERRQ(ierr); 90f7765cecSBarry Smith } 91b4fd4287SBarry Smith 92b4fd4287SBarry Smith for ( j=0; j<n; j++ ) { 93b4fd4287SBarry Smith ierr = VecDot(vec,sp->vecs[j],&sum);CHKERRQ(ierr); 94b4fd4287SBarry Smith sum = -sum; 95b4fd4287SBarry Smith ierr = VecAYPX(&sum,sp->vecs[j],vec); CHKERRQ(ierr); 96f7765cecSBarry Smith } 97b4fd4287SBarry Smith 98f7765cecSBarry Smith return 0; 99f7765cecSBarry Smith } 100