1 #define PETSCMAT_DLL 2 3 /* 4 Routines to project vectors out of null spaces. 5 */ 6 7 #include "src/mat/matimpl.h" /*I "petscmat.h" I*/ 8 #include "petscsys.h" 9 10 PetscCookie PETSCMAT_DLLEXPORT MAT_NULLSPACE_COOKIE = 0; 11 12 #undef __FUNCT__ 13 #define __FUNCT__ "MatNullSpaceCreate" 14 /*@ 15 MatNullSpaceCreate - Creates a data structure used to project vectors 16 out of null spaces. 17 18 Collective on MPI_Comm 19 20 Input Parameters: 21 + comm - the MPI communicator associated with the object 22 . has_cnst - PETSC_TRUE if the null space contains the constant vector; otherwise PETSC_FALSE 23 . n - number of vectors (excluding constant vector) in null space 24 - vecs - the vectors that span the null space (excluding the constant vector); 25 these vectors must be orthonormal. These vectors are NOT copied, so do not change them 26 after this call. You should free the array that you pass in. 27 28 Output Parameter: 29 . SP - the null space context 30 31 Level: advanced 32 33 Users manual sections: 34 . sec_singular 35 36 .keywords: PC, null space, create 37 38 .seealso: MatNullSpaceDestroy(), MatNullSpaceRemove(), KSPSetNullSpace(), MatNullSpace 39 @*/ 40 PetscErrorCode PETSCMAT_DLLEXPORT MatNullSpaceCreate(MPI_Comm comm,PetscTruth has_cnst,PetscInt n,const Vec vecs[],MatNullSpace *SP) 41 { 42 MatNullSpace sp; 43 PetscErrorCode ierr; 44 PetscInt i; 45 46 PetscFunctionBegin; 47 if (n) PetscValidPointer(vecs,4); 48 for (i=0; i<n; i++) PetscValidHeaderSpecific(vecs[i],VEC_COOKIE,4); 49 PetscValidPointer(SP,5); 50 51 *SP = PETSC_NULL; 52 #ifndef PETSC_USE_DYNAMIC_LIBRARIES 53 ierr = MatInitializePackage(PETSC_NULL);CHKERRQ(ierr); 54 #endif 55 56 ierr = PetscHeaderCreate(sp,_p_MatNullSpace,int,MAT_NULLSPACE_COOKIE,0,"MatNullSpace",comm,MatNullSpaceDestroy,0);CHKERRQ(ierr); 57 ierr = PetscLogObjectMemory(sp,sizeof(struct _p_MatNullSpace));CHKERRQ(ierr); 58 59 sp->has_cnst = has_cnst; 60 sp->n = n; 61 sp->vec = PETSC_NULL; 62 if (n) { 63 ierr = PetscMalloc(n*sizeof(Vec),&sp->vecs);CHKERRQ(ierr); 64 for (i=0; i<n; i++) sp->vecs[i] = vecs[i]; 65 } else { 66 sp->vecs = 0; 67 } 68 69 for (i=0; i<n; i++) { 70 ierr = PetscObjectReference((PetscObject)sp->vecs[i]);CHKERRQ(ierr); 71 } 72 *SP = sp; 73 PetscFunctionReturn(0); 74 } 75 76 #undef __FUNCT__ 77 #define __FUNCT__ "MatNullSpaceDestroy" 78 /*@ 79 MatNullSpaceDestroy - Destroys a data structure used to project vectors 80 out of null spaces. 81 82 Collective on MatNullSpace 83 84 Input Parameter: 85 . sp - the null space context to be destroyed 86 87 Level: advanced 88 89 .keywords: PC, null space, destroy 90 91 .seealso: MatNullSpaceCreate(), MatNullSpaceRemove() 92 @*/ 93 PetscErrorCode PETSCMAT_DLLEXPORT MatNullSpaceDestroy(MatNullSpace sp) 94 { 95 PetscErrorCode ierr; 96 97 PetscFunctionBegin; 98 if (--sp->refct > 0) PetscFunctionReturn(0); 99 100 if (sp->vec) {ierr = VecDestroy(sp->vec);CHKERRQ(ierr);} 101 if (sp->vecs) { 102 ierr = VecDestroyVecs(sp->vecs,sp->n);CHKERRQ(ierr); 103 } 104 ierr = PetscHeaderDestroy(sp);CHKERRQ(ierr); 105 PetscFunctionReturn(0); 106 } 107 108 #undef __FUNCT__ 109 #define __FUNCT__ "MatNullSpaceRemove" 110 /*@ 111 MatNullSpaceRemove - Removes all the components of a null space from a vector. 112 113 Collective on MatNullSpace 114 115 Input Parameters: 116 + sp - the null space context 117 . vec - the vector from which the null space is to be removed 118 - out - if this is requested (not PETSC_NULL) then this is a vector with the null space removed otherwise 119 the removal is done in-place (in vec) 120 121 Note: The user is not responsible for the vector returned and should not destroy it. 122 123 Level: advanced 124 125 .keywords: PC, null space, remove 126 127 .seealso: MatNullSpaceCreate(), MatNullSpaceDestroy() 128 @*/ 129 PetscErrorCode PETSCMAT_DLLEXPORT MatNullSpaceRemove(MatNullSpace sp,Vec vec,Vec *out) 130 { 131 PetscScalar sum; 132 PetscErrorCode ierr; 133 PetscInt j,n = sp->n,N; 134 Vec l = vec; 135 136 PetscFunctionBegin; 137 PetscValidHeaderSpecific(sp,MAT_NULLSPACE_COOKIE,1); 138 PetscValidHeaderSpecific(vec,VEC_COOKIE,2); 139 140 if (out) { 141 PetscValidPointer(out,3); 142 if (!sp->vec) { 143 ierr = VecDuplicate(vec,&sp->vec);CHKERRQ(ierr); 144 } 145 *out = sp->vec; 146 ierr = VecCopy(vec,*out);CHKERRQ(ierr); 147 l = *out; 148 } 149 150 if (sp->has_cnst) { 151 ierr = VecSum(l,&sum);CHKERRQ(ierr); 152 ierr = VecGetSize(l,&N);CHKERRQ(ierr); 153 sum = sum/(-1.0*N); 154 ierr = VecShift(l,sum);CHKERRQ(ierr); 155 } 156 157 for (j=0; j<n; j++) { 158 ierr = VecDot(l,sp->vecs[j],&sum);CHKERRQ(ierr); 159 ierr = VecAXPY(l,-sum,sp->vecs[j]);CHKERRQ(ierr); 160 } 161 162 PetscFunctionReturn(0); 163 } 164 165 #undef __FUNCT__ 166 #define __FUNCT__ "MatNullSpaceTest" 167 /*@ 168 MatNullSpaceTest - Tests if the claimed null space is really a 169 null space of a matrix 170 171 Collective on MatNullSpace 172 173 Input Parameters: 174 + sp - the null space context 175 - mat - the matrix 176 177 Level: advanced 178 179 .keywords: PC, null space, remove 180 181 .seealso: MatNullSpaceCreate(), MatNullSpaceDestroy() 182 @*/ 183 PetscErrorCode PETSCMAT_DLLEXPORT MatNullSpaceTest(MatNullSpace sp,Mat mat) 184 { 185 PetscScalar sum; 186 PetscReal nrm; 187 PetscInt j,n = sp->n,N,m; 188 PetscErrorCode ierr; 189 Vec l,r; 190 MPI_Comm comm = sp->comm; 191 PetscTruth flg1,flg2; 192 193 PetscFunctionBegin; 194 ierr = PetscOptionsHasName(PETSC_NULL,"-mat_null_space_test_view",&flg1);CHKERRQ(ierr); 195 ierr = PetscOptionsHasName(PETSC_NULL,"-mat_null_space_test_view_draw",&flg2);CHKERRQ(ierr); 196 197 if (!sp->vec) { 198 if (n) { 199 ierr = VecDuplicate(sp->vecs[0],&sp->vec);CHKERRQ(ierr); 200 } else { 201 ierr = MatGetLocalSize(mat,&m,PETSC_NULL);CHKERRQ(ierr); 202 ierr = VecCreateMPI(sp->comm,m,PETSC_DETERMINE,&sp->vec);CHKERRQ(ierr); 203 } 204 } 205 l = sp->vec; 206 207 if (sp->has_cnst) { 208 ierr = VecDuplicate(l,&r);CHKERRQ(ierr); 209 ierr = VecGetSize(l,&N);CHKERRQ(ierr); 210 sum = 1.0/N; 211 ierr = VecSet(l,sum);CHKERRQ(ierr); 212 ierr = MatMult(mat,l,r);CHKERRQ(ierr); 213 ierr = VecNorm(r,NORM_2,&nrm);CHKERRQ(ierr); 214 if (nrm < 1.e-7) {ierr = PetscPrintf(comm,"Constants are likely null vector");CHKERRQ(ierr);} 215 else {ierr = PetscPrintf(comm,"Constants are unlikely null vector ");CHKERRQ(ierr);} 216 ierr = PetscPrintf(comm,"|| A * 1 || = %g\n",nrm);CHKERRQ(ierr); 217 if (nrm > 1.e-7 && flg1) {ierr = VecView(r,PETSC_VIEWER_STDOUT_(comm));CHKERRQ(ierr);} 218 if (nrm > 1.e-7 && flg2) {ierr = VecView(r,PETSC_VIEWER_DRAW_(comm));CHKERRQ(ierr);} 219 ierr = VecDestroy(r);CHKERRQ(ierr); 220 } 221 222 for (j=0; j<n; j++) { 223 ierr = (*mat->ops->mult)(mat,sp->vecs[j],l);CHKERRQ(ierr); 224 ierr = VecNorm(l,NORM_2,&nrm);CHKERRQ(ierr); 225 if (nrm < 1.e-7) {ierr = PetscPrintf(comm,"Null vector %D is likely null vector",j);CHKERRQ(ierr);} 226 else {ierr = PetscPrintf(comm,"Null vector %D unlikely null vector ",j);CHKERRQ(ierr);} 227 ierr = PetscPrintf(comm,"|| A * v[%D] || = %g\n",j,nrm);CHKERRQ(ierr); 228 if (nrm > 1.e-7 && flg1) {ierr = VecView(l,PETSC_VIEWER_STDOUT_(comm));CHKERRQ(ierr);} 229 if (nrm > 1.e-7 && flg2) {ierr = VecView(l,PETSC_VIEWER_DRAW_(comm));CHKERRQ(ierr);} 230 } 231 232 PetscFunctionReturn(0); 233 } 234 235