xref: /petsc/src/mat/impls/baij/seq/baijfact4.c (revision 6abefa4f446b2ea91915da4e25ea0defa83db48e)
1 #define PETSCMAT_DLL
2 
3 /*
4     Factorization code for BAIJ format.
5 */
6 #include "../src/mat/impls/baij/seq/baij.h"
7 #include "../src/mat/blockinvert.h"
8 
9 /* ----------------------------------------------------------- */
10 #undef __FUNCT__
11 #define __FUNCT__ "MatLUFactorNumeric_SeqBAIJ_N_inplace"
12 PetscErrorCode MatLUFactorNumeric_SeqBAIJ_N_inplace(Mat C,Mat A,const MatFactorInfo *info)
13 {
14   Mat_SeqBAIJ    *a = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ *)C->data;
15   IS             isrow = b->row,isicol = b->icol;
16   PetscErrorCode ierr;
17   const PetscInt *r,*ic;
18   PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
19   PetscInt       *ajtmpold,*ajtmp,nz,row,bslog,*ai=a->i,*aj=a->j,k,flg;
20   PetscInt       *diag_offset=b->diag,diag,bs=A->rmap->bs,bs2 = a->bs2,*pj,*v_pivots;
21   MatScalar      *ba = b->a,*aa = a->a,*pv,*v,*rtmp,*multiplier,*v_work,*pc,*w;
22 
23   PetscFunctionBegin;
24   ierr = ISGetIndices(isrow,&r);CHKERRQ(ierr);
25   ierr = ISGetIndices(isicol,&ic);CHKERRQ(ierr);
26   ierr = PetscMalloc(bs2*(n+1)*sizeof(MatScalar),&rtmp);CHKERRQ(ierr);
27   ierr = PetscMemzero(rtmp,(bs2*n+1)*sizeof(MatScalar));CHKERRQ(ierr);
28   /* generate work space needed by dense LU factorization */
29   ierr = PetscMalloc3(bs,MatScalar,&v_work,bs2,MatScalar,&multiplier,bs,PetscInt,&v_pivots);CHKERRQ(ierr);
30 
31   /* flops in while loop */
32   bslog = 2*bs*bs2;
33 
34   for (i=0; i<n; i++) {
35     nz    = bi[i+1] - bi[i];
36     ajtmp = bj + bi[i];
37     for  (j=0; j<nz; j++) {
38       ierr = PetscMemzero(rtmp+bs2*ajtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
39     }
40     /* load in initial (unfactored row) */
41     nz       = ai[r[i]+1] - ai[r[i]];
42     ajtmpold = aj + ai[r[i]];
43     v        = aa + bs2*ai[r[i]];
44     for (j=0; j<nz; j++) {
45       ierr = PetscMemcpy(rtmp+bs2*ic[ajtmpold[j]],v+bs2*j,bs2*sizeof(MatScalar));CHKERRQ(ierr);
46     }
47     row = *ajtmp++;
48     while (row < i) {
49       pc = rtmp + bs2*row;
50 /*      if (*pc) { */
51       for (flg=0,k=0; k<bs2; k++) { if (pc[k]!=0.0) { flg = 1; break; }}
52       if (flg) {
53         pv = ba + bs2*diag_offset[row];
54         pj = bj + diag_offset[row] + 1;
55         Kernel_A_gets_A_times_B(bs,pc,pv,multiplier);
56         nz = bi[row+1] - diag_offset[row] - 1;
57         pv += bs2;
58         for (j=0; j<nz; j++) {
59           Kernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j);
60         }
61         ierr = PetscLogFlops(bslog*(nz+1.0)-bs);CHKERRQ(ierr);
62       }
63         row = *ajtmp++;
64     }
65     /* finished row so stick it into b->a */
66     pv = ba + bs2*bi[i];
67     pj = bj + bi[i];
68     nz = bi[i+1] - bi[i];
69     for (j=0; j<nz; j++) {
70       ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
71     }
72     diag = diag_offset[i] - bi[i];
73     /* invert diagonal block */
74     w = pv + bs2*diag;
75     ierr = Kernel_A_gets_inverse_A(bs,w,v_pivots,v_work);CHKERRQ(ierr);
76   }
77 
78   ierr = PetscFree(rtmp);CHKERRQ(ierr);
79   ierr = PetscFree3(v_work,multiplier,v_pivots);CHKERRQ(ierr);
80   ierr = ISRestoreIndices(isicol,&ic);CHKERRQ(ierr);
81   ierr = ISRestoreIndices(isrow,&r);CHKERRQ(ierr);
82   C->ops->solve          = MatSolve_SeqBAIJ_N_inplace;
83   C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_N_inplace;
84   C->assembled  = PETSC_TRUE;
85   ierr = PetscLogFlops(1.333333333333*bs*bs2*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
86   PetscFunctionReturn(0);
87 }
88