1f7765cecSBarry Smith #ifndef lint 2*70f55243SBarry Smith static char vcid[] = "$Id: pcnull.c,v 1.5 1996/04/25 23:59:27 balay Exp bsmith $"; 3f7765cecSBarry Smith #endif 4f7765cecSBarry Smith /* 5b4fd4287SBarry Smith Routines to project vectors out of null spaces. 6f7765cecSBarry Smith */ 7f7765cecSBarry Smith 8f7765cecSBarry Smith #include "petsc.h" 9*70f55243SBarry 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 15112a2221SBarry Smith /*@C 16b4fd4287SBarry Smith PCNullSpaceCreate - Creates a data-structure used to project vectors 17b4fd4287SBarry Smith out of null spaces. 18f7765cecSBarry Smith 19f7765cecSBarry Smith Input Parameters: 20b4fd4287SBarry Smith . comm - the MPI communicator associated with the object. 21b4fd4287SBarry Smith . has_cnst - if the null spaces contains the constant vector, PETSC_TRUE or PETSC_FALSE 22b4fd4287SBarry Smith . n - number of vectors (excluding constant vector) in null space 23b4fd4287SBarry Smith . vecs - the vectors that span the null space (excluding the constant vector) 24b4fd4287SBarry Smith . these vectors must be orthonormal 25f7765cecSBarry Smith 26f7765cecSBarry Smith Output Parameter: 27b4fd4287SBarry Smith . SP - the null space context 28f7765cecSBarry Smith 29f7765cecSBarry Smith 30b4fd4287SBarry Smith .keywords: PC, Null space 31f7765cecSBarry Smith @*/ 32b4fd4287SBarry Smith int PCNullSpaceCreate(MPI_Comm comm, int has_cnst, int n, Vec *vecs,PCNullSpace *SP) 33f7765cecSBarry Smith { 34b4fd4287SBarry Smith PCNullSpace sp; 35f7765cecSBarry Smith 36b4fd4287SBarry Smith PetscHeaderCreate(sp,_PCNullSpace,PCNULLSPACE_COOKIE,0,comm); 37b4fd4287SBarry Smith PLogObjectCreate(sp); 38b4fd4287SBarry Smith PLogObjectMemory(sp,sizeof(struct _PCNullSpace)); 39f7765cecSBarry Smith 40b4fd4287SBarry Smith sp->has_cnst = has_cnst; 41b4fd4287SBarry Smith sp->n = n; 42b4fd4287SBarry Smith sp->vecs = vecs; 43b4fd4287SBarry Smith 44b4fd4287SBarry Smith *SP = sp; 45f7765cecSBarry Smith return 0; 46f7765cecSBarry Smith } 47f7765cecSBarry Smith 48f7765cecSBarry Smith /*@ 49b4fd4287SBarry Smith PCNullSpaceDestroy - Destroys a data-structure used to project vectors 50b4fd4287SBarry Smith out of null spaces. 51b4fd4287SBarry Smith 52b4fd4287SBarry Smith Input Parameter: 53b4fd4287SBarry Smith . SP - the null space context to be destroyed 54b4fd4287SBarry Smith 55b4fd4287SBarry Smith .keywords: PC, Null space 56b4fd4287SBarry Smith @*/ 57b4fd4287SBarry Smith int PCNullSpaceDestroy(PCNullSpace sp) 58b4fd4287SBarry Smith { 59b4fd4287SBarry Smith PLogObjectDestroy(sp); 60b4fd4287SBarry Smith PetscHeaderDestroy(sp); 61b4fd4287SBarry Smith return 0; 62b4fd4287SBarry Smith } 63b4fd4287SBarry Smith 64b4fd4287SBarry Smith /*@ 65b4fd4287SBarry Smith PCNullSpaceRemove - Removes all the components of a null space from a vector. 66f7765cecSBarry Smith 67f7765cecSBarry Smith Input Parameters: 68b4fd4287SBarry Smith . sp - the null space context 69b4fd4287SBarry Smith . vec - the vector you want the null space removed from 70f7765cecSBarry Smith 71f7765cecSBarry Smith 72b4fd4287SBarry Smith .keywords: PC, Null space 73f7765cecSBarry Smith @*/ 74b4fd4287SBarry Smith int PCNullSpaceRemove(PCNullSpace sp,Vec vec) 75f7765cecSBarry Smith { 76b4fd4287SBarry Smith Scalar sum; 77b4fd4287SBarry Smith int j, n = sp->n, N,ierr; 78f7765cecSBarry Smith 79b4fd4287SBarry Smith if (sp->has_cnst) { 80b4fd4287SBarry Smith ierr = VecSum(vec,&sum); CHKERRQ(ierr); 81b4fd4287SBarry Smith ierr = VecGetSize(vec,&N); CHKERRQ(ierr); 82b4fd4287SBarry Smith sum = -sum/N; 83b4fd4287SBarry Smith ierr = VecShift(&sum,vec); CHKERRQ(ierr); 84f7765cecSBarry Smith } 85b4fd4287SBarry Smith 86b4fd4287SBarry Smith for ( j=0; j<n; j++ ) { 87b4fd4287SBarry Smith ierr = VecDot(vec,sp->vecs[j],&sum);CHKERRQ(ierr); 88b4fd4287SBarry Smith sum = -sum; 89b4fd4287SBarry Smith ierr = VecAYPX(&sum,sp->vecs[j],vec); CHKERRQ(ierr); 90f7765cecSBarry Smith } 91b4fd4287SBarry Smith 92f7765cecSBarry Smith return 0; 93f7765cecSBarry Smith } 94