Actual source code: symtranspose.c

  1: /*
  2:   Defines transpose routines for SeqAIJ matrices.
  3: */

  5: #include <../src/mat/impls/aij/seq/aij.h>

  7: /*
  8:    The symbolic and full transpose versions share several similar code blocks but the macros to reuse the code would be confusing and ugly
  9: */
 10: PetscErrorCode MatTransposeSymbolic_SeqAIJ(Mat A, Mat *B)
 11: {
 12:   PetscInt    i, j, anzj;
 13:   Mat         At;
 14:   Mat_SeqAIJ *a  = (Mat_SeqAIJ *)A->data, *at;
 15:   PetscInt    an = A->cmap->N, am = A->rmap->N;
 16:   PetscInt   *ati, *atj, *atfill, *ai = a->i, *aj = a->j;

 18:   PetscFunctionBegin;
 19:   /* Allocate space for symbolic transpose info and work array */
 20:   PetscCall(PetscCalloc1(an + 1, &ati));
 21:   PetscCall(PetscMalloc1(ai[am], &atj));

 23:   /* Walk through aj and count ## of non-zeros in each row of A^T. */
 24:   /* Note: offset by 1 for fast conversion into csr format. */
 25:   for (i = 0; i < ai[am]; i++) ati[aj[i] + 1] += 1;
 26:   /* Form ati for csr format of A^T. */
 27:   for (i = 0; i < an; i++) ati[i + 1] += ati[i];

 29:   /* Copy ati into atfill so we have locations of the next free space in atj */
 30:   PetscCall(PetscMalloc1(an, &atfill));
 31:   PetscCall(PetscArraycpy(atfill, ati, an));

 33:   /* Walk through A row-wise and mark nonzero entries of A^T. */
 34:   for (i = 0; i < am; i++) {
 35:     anzj = ai[i + 1] - ai[i];
 36:     for (j = 0; j < anzj; j++) {
 37:       atj[atfill[*aj]] = i;
 38:       atfill[*aj++] += 1;
 39:     }
 40:   }
 41:   PetscCall(PetscFree(atfill));

 43:   PetscCall(MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A), an, am, ati, atj, NULL, &At));
 44:   PetscCall(MatSetBlockSizes(At, PetscAbs(A->cmap->bs), PetscAbs(A->rmap->bs)));
 45:   PetscCall(MatSetType(At, ((PetscObject)A)->type_name));
 46:   at          = (Mat_SeqAIJ *)At->data;
 47:   at->free_a  = PETSC_FALSE;
 48:   at->free_ij = PETSC_TRUE;
 49:   at->nonew   = 0;
 50:   at->maxnz   = ati[an];
 51:   *B          = At;
 52:   PetscFunctionReturn(PETSC_SUCCESS);
 53: }

 55: PetscErrorCode MatTranspose_SeqAIJ(Mat A, MatReuse reuse, Mat *B)
 56: {
 57:   PetscInt         i, j, anzj;
 58:   Mat              At;
 59:   Mat_SeqAIJ      *a  = (Mat_SeqAIJ *)A->data, *at;
 60:   PetscInt         an = A->cmap->N, am = A->rmap->N;
 61:   PetscInt        *ati, *atj, *atfill, *ai = a->i, *aj = a->j;
 62:   MatScalar       *ata;
 63:   const MatScalar *aa, *av;
 64:   PetscContainer   rB;
 65:   MatParentState  *rb;
 66:   PetscBool        nonzerochange = PETSC_FALSE;

 68:   PetscFunctionBegin;
 69:   if (reuse == MAT_REUSE_MATRIX) {
 70:     PetscCall(PetscObjectQuery((PetscObject)*B, "MatTransposeParent", (PetscObject *)&rB));
 71:     PetscCheck(rB, PetscObjectComm((PetscObject)*B), PETSC_ERR_ARG_WRONG, "Reuse matrix used was not generated from call to MatTranspose()");
 72:     PetscCall(PetscContainerGetPointer(rB, (void **)&rb));
 73:     if (rb->nonzerostate != A->nonzerostate) nonzerochange = PETSC_TRUE;
 74:   }

 76:   PetscCall(MatSeqAIJGetArrayRead(A, &av));
 77:   aa = av;
 78:   if (reuse == MAT_INITIAL_MATRIX || reuse == MAT_INPLACE_MATRIX || nonzerochange) {
 79:     /* Allocate space for symbolic transpose info and work array */
 80:     PetscCall(PetscCalloc1(an + 1, &ati));
 81:     PetscCall(PetscMalloc1(ai[am], &atj));
 82:     /* Walk through aj and count ## of non-zeros in each row of A^T. */
 83:     /* Note: offset by 1 for fast conversion into csr format. */
 84:     for (i = 0; i < ai[am]; i++) ati[aj[i] + 1] += 1;
 85:     /* Form ati for csr format of A^T. */
 86:     for (i = 0; i < an; i++) ati[i + 1] += ati[i];
 87:     PetscCall(PetscMalloc1(ai[am], &ata));
 88:   } else {
 89:     Mat_SeqAIJ *sub_B = (Mat_SeqAIJ *)(*B)->data;
 90:     ati               = sub_B->i;
 91:     atj               = sub_B->j;
 92:     ata               = sub_B->a;
 93:     At                = *B;
 94:   }

 96:   /* Copy ati into atfill so we have locations of the next free space in atj */
 97:   PetscCall(PetscMalloc1(an, &atfill));
 98:   PetscCall(PetscArraycpy(atfill, ati, an));

100:   /* Walk through A row-wise and mark nonzero entries of A^T. */
101:   for (i = 0; i < am; i++) {
102:     anzj = ai[i + 1] - ai[i];
103:     for (j = 0; j < anzj; j++) {
104:       atj[atfill[*aj]] = i;
105:       ata[atfill[*aj]] = *aa++;
106:       atfill[*aj++] += 1;
107:     }
108:   }
109:   PetscCall(PetscFree(atfill));
110:   PetscCall(MatSeqAIJRestoreArrayRead(A, &av));
111:   if (reuse == MAT_REUSE_MATRIX) PetscCall(PetscObjectStateIncrease((PetscObject)*B));

113:   if (reuse == MAT_INITIAL_MATRIX || reuse == MAT_INPLACE_MATRIX || nonzerochange) {
114:     PetscCall(MatCreateSeqAIJWithArrays(PetscObjectComm((PetscObject)A), an, am, ati, atj, ata, &At));
115:     PetscCall(MatSetBlockSizes(At, PetscAbs(A->cmap->bs), PetscAbs(A->rmap->bs)));
116:     PetscCall(MatSetType(At, ((PetscObject)A)->type_name));
117:     at          = (Mat_SeqAIJ *)At->data;
118:     at->free_a  = PETSC_TRUE;
119:     at->free_ij = PETSC_TRUE;
120:     at->nonew   = 0;
121:     at->maxnz   = ati[an];
122:   }

124:   if (reuse == MAT_INITIAL_MATRIX || (reuse == MAT_REUSE_MATRIX && !nonzerochange)) {
125:     *B = At;
126:   } else if (nonzerochange) {
127:     PetscCall(MatHeaderMerge(*B, &At));
128:     PetscCall(MatTransposeSetPrecursor(A, *B));
129:   } else if (reuse == MAT_INPLACE_MATRIX) {
130:     PetscCall(MatHeaderMerge(A, &At));
131:   }
132:   PetscFunctionReturn(PETSC_SUCCESS);
133: }

135: /*
136:    Get symbolic matrix structure of a submatrix of A, A[rstart:rend,:],
137: */
138: PetscErrorCode MatGetSymbolicTransposeReduced_SeqAIJ(Mat A, PetscInt rstart, PetscInt rend, PetscInt *Ati[], PetscInt *Atj[])
139: {
140:   PetscInt    i, j, anzj;
141:   Mat_SeqAIJ *a  = (Mat_SeqAIJ *)A->data;
142:   PetscInt    an = A->cmap->N;
143:   PetscInt   *ati, *atj, *atfill, *ai = a->i, *aj = a->j, am = ai[rend] - ai[rstart];

145:   PetscFunctionBegin;
146:   PetscCall(PetscLogEventBegin(MAT_Getsymtransreduced, A, 0, 0, 0));

148:   /* Allocate space for symbolic transpose info and work array */
149:   PetscCall(PetscCalloc1(an + 1, &ati));
150:   PetscCall(PetscMalloc1(am + 1, &atj));

152:   /* Walk through aj and count ## of non-zeros in each row of A^T. */
153:   /* Note: offset by 1 for fast conversion into csr format. */
154:   for (i = ai[rstart]; i < ai[rend]; i++) ati[aj[i] + 1] += 1;
155:   /* Form ati for csr format of A^T. */
156:   for (i = 0; i < an; i++) ati[i + 1] += ati[i];

158:   /* Copy ati into atfill so we have locations of the next free space in atj */
159:   PetscCall(PetscMalloc1(an + 1, &atfill));
160:   PetscCall(PetscArraycpy(atfill, ati, an));

162:   /* Walk through A row-wise and mark nonzero entries of A^T. */
163:   aj = PetscSafePointerPlusOffset(aj, ai[rstart]);
164:   for (i = rstart; i < rend; i++) {
165:     anzj = ai[i + 1] - ai[i];
166:     for (j = 0; j < anzj; j++) {
167:       atj[atfill[*aj]] = i - rstart;
168:       atfill[*aj++] += 1;
169:     }
170:   }
171:   PetscCall(PetscFree(atfill));
172:   *Ati = ati;
173:   *Atj = atj;

175:   PetscCall(PetscLogEventEnd(MAT_Getsymtransreduced, A, 0, 0, 0));
176:   PetscFunctionReturn(PETSC_SUCCESS);
177: }

179: /*
180:     Returns the i and j arrays for a symbolic transpose, this is used internally within SeqAIJ code when the full
181:     symbolic matrix (which can be obtained with MatTransposeSymbolic() is not needed. MatRestoreSymbolicTranspose_SeqAIJ() should be used to free the arrays.
182: */
183: PetscErrorCode MatGetSymbolicTranspose_SeqAIJ(Mat A, PetscInt *Ati[], PetscInt *Atj[])
184: {
185:   PetscFunctionBegin;
186:   PetscCall(MatGetSymbolicTransposeReduced_SeqAIJ(A, 0, A->rmap->N, Ati, Atj));
187:   PetscFunctionReturn(PETSC_SUCCESS);
188: }

190: PetscErrorCode MatRestoreSymbolicTranspose_SeqAIJ(Mat A, PetscInt *ati[], PetscInt *atj[])
191: {
192:   PetscFunctionBegin;
193:   PetscCall(PetscFree(*ati));
194:   PetscCall(PetscFree(*atj));
195:   PetscFunctionReturn(PETSC_SUCCESS);
196: }