Date: 2022-03-04T17:37:49+00:00

Actual source code: baijfact4.c

      2: /*
      3:     Factorization code for BAIJ format.
      4: */
      5: #include <../src/mat/impls/baij/seq/baij.h>
      6: #include <petsc/private/kernels/blockinvert.h>

      8: /* ----------------------------------------------------------- */
      9: PetscErrorCode MatLUFactorNumeric_SeqBAIJ_N_inplace(Mat C,Mat A,const MatFactorInfo *info)
     10: {
     11:   Mat_SeqBAIJ    *a    = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ*)C->data;
     12:   IS             isrow = b->row,isicol = b->icol;
     14:   const PetscInt *r,*ic;
     15:   PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
     16:   PetscInt       *ajtmpold,*ajtmp,nz,row,*ai=a->i,*aj=a->j,k,flg;
     17:   PetscInt       *diag_offset=b->diag,diag,bs=A->rmap->bs,bs2 = a->bs2,*pj,*v_pivots;
     18:   MatScalar      *ba = b->a,*aa = a->a,*pv,*v,*rtmp,*multiplier,*v_work,*pc,*w;
     19:   PetscBool      allowzeropivot,zeropivotdetected;

     22:   ISGetIndices(isrow,&r);
     23:   ISGetIndices(isicol,&ic);
     24:   allowzeropivot = PetscNot(A->erroriffailure);

     26:   PetscCalloc1(bs2*(n+1),&rtmp);
     27:   /* generate work space needed by dense LU factorization */
     28:   PetscMalloc3(bs,&v_work,bs2,&multiplier,bs,&v_pivots);

     30:   for (i=0; i<n; i++) {
     31:     nz    = bi[i+1] - bi[i];
     32:     ajtmp = bj + bi[i];
     33:     for  (j=0; j<nz; j++) {
     34:       PetscArrayzero(rtmp+bs2*ajtmp[j],bs2);
     35:     }
     36:     /* load in initial (unfactored row) */
     37:     nz       = ai[r[i]+1] - ai[r[i]];
     38:     ajtmpold = aj + ai[r[i]];
     39:     v        = aa + bs2*ai[r[i]];
     40:     for (j=0; j<nz; j++) {
     41:       PetscArraycpy(rtmp+bs2*ic[ajtmpold[j]],v+bs2*j,bs2);
     42:     }
     43:     row = *ajtmp++;
     44:     while (row < i) {
     45:       pc = rtmp + bs2*row;
     46: /*      if (*pc) { */
     47:       for (flg=0,k=0; k<bs2; k++) {
     48:         if (pc[k]!=0.0) {
     49:           flg = 1;
     50:           break;
     51:         }
     52:       }
     53:       if (flg) {
     54:         pv = ba + bs2*diag_offset[row];
     55:         pj = bj + diag_offset[row] + 1;
     56:         PetscKernel_A_gets_A_times_B(bs,pc,pv,multiplier);
     57:         nz  = bi[row+1] - diag_offset[row] - 1;
     58:         pv += bs2;
     59:         for (j=0; j<nz; j++) {
     60:           PetscKernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j);
     61:         }
     62:         PetscLogFlops(2.0*bs*bs2*(nz+1.0)-bs);
     63:       }
     64:       row = *ajtmp++;
     65:     }
     66:     /* finished row so stick it into b->a */
     67:     pv = ba + bs2*bi[i];
     68:     pj = bj + bi[i];
     69:     nz = bi[i+1] - bi[i];
     70:     for (j=0; j<nz; j++) {
     71:       PetscArraycpy(pv+bs2*j,rtmp+bs2*pj[j],bs2);
     72:     }
     73:     diag = diag_offset[i] - bi[i];
     74:     /* invert diagonal block */
     75:     w    = pv + bs2*diag;

     77:     PetscKernel_A_gets_inverse_A(bs,w,v_pivots,v_work,allowzeropivot,&zeropivotdetected);
     78:     if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
     79:   }

     81:   PetscFree(rtmp);
     82:   PetscFree3(v_work,multiplier,v_pivots);
     83:   ISRestoreIndices(isicol,&ic);
     84:   ISRestoreIndices(isrow,&r);

     86:   C->ops->solve          = MatSolve_SeqBAIJ_N_inplace;
     87:   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_N_inplace;
     88:   C->assembled           = PETSC_TRUE;

     90:   PetscLogFlops(1.333333333333*bs*bs2*b->mbs); /* from inverting diagonal blocks */
     91:   return(0);
     92: }