xref: /petsc/src/mat/impls/sbaij/seq/sbaijfact3.c (revision 2205254efee3a00a594e5e2a3a70f74dcb40bc03)
1 
2 #include <../src/mat/impls/sbaij/seq/sbaij.h>
3 #include <../src/mat/blockinvert.h>
4 
5 /* Version for when blocks are 3 by 3  */
6 #undef __FUNCT__
7 #define __FUNCT__ "MatCholeskyFactorNumeric_SeqSBAIJ_3"
8 PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_3(Mat C,Mat A,const MatFactorInfo *info)
9 {
10   Mat_SeqSBAIJ   *a = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ *)C->data;
11   IS             perm = b->row;
12   PetscErrorCode ierr;
13   const PetscInt *ai,*aj,*perm_ptr,mbs=a->mbs,*bi=b->i,*bj=b->j;
14   PetscInt       *a2anew,i,j,k,k1,jmin,jmax,*jl,*il,vj,nexti,ili;
15   MatScalar      *ba = b->a,*aa,*ap,*dk,*uik;
16   MatScalar      *u,*diag,*rtmp,*rtmp_ptr;
17   PetscReal      shift = info->shiftamount;
18 
19   PetscFunctionBegin;
20   /* initialization */
21   ierr = PetscMalloc(9*mbs*sizeof(MatScalar),&rtmp);CHKERRQ(ierr);
22   ierr = PetscMemzero(rtmp,9*mbs*sizeof(MatScalar));CHKERRQ(ierr);
23   ierr = PetscMalloc2(mbs,PetscInt,&il,mbs,PetscInt,&jl);CHKERRQ(ierr);
24   for (i=0; i<mbs; i++) {
25     jl[i] = mbs; il[0] = 0;
26   }
27   ierr = PetscMalloc2(9,MatScalar,&dk,9,MatScalar,&uik);CHKERRQ(ierr);
28   ierr = ISGetIndices(perm,&perm_ptr);CHKERRQ(ierr);
29 
30   /* check permutation */
31   if (!a->permute) {
32     ai = a->i; aj = a->j; aa = a->a;
33   } else {
34     ai   = a->inew; aj = a->jnew;
35     ierr = PetscMalloc(9*ai[mbs]*sizeof(MatScalar),&aa);CHKERRQ(ierr);
36     ierr = PetscMemcpy(aa,a->a,9*ai[mbs]*sizeof(MatScalar));CHKERRQ(ierr);
37     ierr = PetscMalloc(ai[mbs]*sizeof(PetscInt),&a2anew);CHKERRQ(ierr);
38     ierr = PetscMemcpy(a2anew,a->a2anew,(ai[mbs])*sizeof(PetscInt));CHKERRQ(ierr);
39 
40     for (i=0; i<mbs; i++) {
41       jmin = ai[i]; jmax = ai[i+1];
42       for (j=jmin; j<jmax; j++) {
43         while (a2anew[j] != j) {
44           k = a2anew[j]; a2anew[j] = a2anew[k]; a2anew[k] = k;
45           for (k1=0; k1<9; k1++) {
46             dk[k1]       = aa[k*9+k1];
47             aa[k*9+k1] = aa[j*9+k1];
48             aa[j*9+k1] = dk[k1];
49           }
50         }
51         /* transform columnoriented blocks that lie in the lower triangle to roworiented blocks */
52         if (i > aj[j]) {
53           /* printf("change orientation, row: %d, col: %d\n",i,aj[j]); */
54           ap = aa + j*9;                     /* ptr to the beginning of j-th block of aa */
55           for (k=0; k<9; k++) dk[k] = ap[k]; /* dk <- j-th block of aa */
56           for (k=0; k<3; k++) {               /* j-th block of aa <- dk^T */
57             for (k1=0; k1<3; k1++) *ap++ = dk[k + 3*k1];
58           }
59         }
60       }
61     }
62     ierr = PetscFree(a2anew);CHKERRQ(ierr);
63   }
64 
65   /* for each row k */
66   for (k = 0; k<mbs; k++) {
67 
68     /*initialize k-th row with elements nonzero in row perm(k) of A */
69     jmin = ai[perm_ptr[k]]; jmax = ai[perm_ptr[k]+1];
70     if (jmin < jmax) {
71       ap = aa + jmin*9;
72       for (j = jmin; j < jmax; j++) {
73         vj = perm_ptr[aj[j]];         /* block col. index */
74         rtmp_ptr = rtmp + vj*9;
75         for (i=0; i<9; i++) *rtmp_ptr++ = *ap++;
76       }
77     }
78 
79     /* modify k-th row by adding in those rows i with U(i,k) != 0 */
80     ierr = PetscMemcpy(dk,rtmp+k*9,9*sizeof(MatScalar));CHKERRQ(ierr);
81     i = jl[k]; /* first row to be added to k_th row  */
82 
83     while (i < mbs) {
84       nexti = jl[i]; /* next row to be added to k_th row */
85 
86       /* compute multiplier */
87       ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */
88 
89       /* uik = -inv(Di)*U_bar(i,k) */
90       diag = ba + i*9;
91       u    = ba + ili*9;
92 
93       uik[0] = -(diag[0]*u[0] + diag[3]*u[1] + diag[6]*u[2]);
94       uik[1] = -(diag[1]*u[0] + diag[4]*u[1] + diag[7]*u[2]);
95       uik[2] = -(diag[2]*u[0] + diag[5]*u[1] + diag[8]*u[2]);
96 
97       uik[3] = -(diag[0]*u[3] + diag[3]*u[4] + diag[6]*u[5]);
98       uik[4] = -(diag[1]*u[3] + diag[4]*u[4] + diag[7]*u[5]);
99       uik[5] = -(diag[2]*u[3] + diag[5]*u[4] + diag[8]*u[5]);
100 
101       uik[6] = -(diag[0]*u[6] + diag[3]*u[7] + diag[6]*u[8]);
102       uik[7] = -(diag[1]*u[6] + diag[4]*u[7] + diag[7]*u[8]);
103       uik[8] = -(diag[2]*u[6] + diag[5]*u[7] + diag[8]*u[8]);
104 
105       /* update D(k) += -U(i,k)^T * U_bar(i,k) */
106       dk[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2];
107       dk[1] += uik[3]*u[0] + uik[4]*u[1] + uik[5]*u[2];
108       dk[2] += uik[6]*u[0] + uik[7]*u[1] + uik[8]*u[2];
109 
110       dk[3] += uik[0]*u[3] + uik[1]*u[4] + uik[2]*u[5];
111       dk[4] += uik[3]*u[3] + uik[4]*u[4] + uik[5]*u[5];
112       dk[5] += uik[6]*u[3] + uik[7]*u[4] + uik[8]*u[5];
113 
114       dk[6] += uik[0]*u[6] + uik[1]*u[7] + uik[2]*u[8];
115       dk[7] += uik[3]*u[6] + uik[4]*u[7] + uik[5]*u[8];
116       dk[8] += uik[6]*u[6] + uik[7]*u[7] + uik[8]*u[8];
117 
118       ierr = PetscLogFlops(27.0*4.0);CHKERRQ(ierr);
119 
120       /* update -U(i,k) */
121       ierr = PetscMemcpy(ba+ili*9,uik,9*sizeof(MatScalar));CHKERRQ(ierr);
122 
123       /* add multiple of row i to k-th row ... */
124       jmin = ili + 1; jmax = bi[i+1];
125       if (jmin < jmax) {
126         for (j=jmin; j<jmax; j++) {
127           /* rtmp += -U(i,k)^T * U_bar(i,j) */
128           rtmp_ptr = rtmp + bj[j]*9;
129           u = ba + j*9;
130           rtmp_ptr[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2];
131           rtmp_ptr[1] += uik[3]*u[0] + uik[4]*u[1] + uik[5]*u[2];
132           rtmp_ptr[2] += uik[6]*u[0] + uik[7]*u[1] + uik[8]*u[2];
133 
134           rtmp_ptr[3] += uik[0]*u[3] + uik[1]*u[4] + uik[2]*u[5];
135           rtmp_ptr[4] += uik[3]*u[3] + uik[4]*u[4] + uik[5]*u[5];
136           rtmp_ptr[5] += uik[6]*u[3] + uik[7]*u[4] + uik[8]*u[5];
137 
138           rtmp_ptr[6] += uik[0]*u[6] + uik[1]*u[7] + uik[2]*u[8];
139           rtmp_ptr[7] += uik[3]*u[6] + uik[4]*u[7] + uik[5]*u[8];
140           rtmp_ptr[8] += uik[6]*u[6] + uik[7]*u[7] + uik[8]*u[8];
141         }
142         ierr = PetscLogFlops(2.0*27.0*(jmax-jmin));CHKERRQ(ierr);
143 
144         /* ... add i to row list for next nonzero entry */
145         il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
146         j     = bj[jmin];
147         jl[i] = jl[j]; jl[j] = i; /* update jl */
148       }
149       i = nexti;
150     }
151 
152     /* save nonzero entries in k-th row of U ... */
153 
154     /* invert diagonal block */
155     diag = ba+k*9;
156     ierr = PetscMemcpy(diag,dk,9*sizeof(MatScalar));CHKERRQ(ierr);
157     ierr = PetscKernel_A_gets_inverse_A_3(diag,shift);CHKERRQ(ierr);
158 
159     jmin = bi[k]; jmax = bi[k+1];
160     if (jmin < jmax) {
161       for (j=jmin; j<jmax; j++) {
162          vj = bj[j];           /* block col. index of U */
163          u   = ba + j*9;
164          rtmp_ptr = rtmp + vj*9;
165          for (k1=0; k1<9; k1++) {
166            *u++        = *rtmp_ptr;
167            *rtmp_ptr++ = 0.0;
168          }
169       }
170 
171       /* ... add k to row list for first nonzero entry in k-th row */
172       il[k] = jmin;
173       i     = bj[jmin];
174       jl[k] = jl[i]; jl[i] = k;
175     }
176   }
177 
178   ierr = PetscFree(rtmp);CHKERRQ(ierr);
179   ierr = PetscFree2(il,jl);CHKERRQ(ierr);
180   ierr = PetscFree2(dk,uik);CHKERRQ(ierr);
181   if (a->permute) {
182     ierr = PetscFree(aa);CHKERRQ(ierr);
183   }
184 
185   ierr = ISRestoreIndices(perm,&perm_ptr);CHKERRQ(ierr);
186   C->ops->solve          = MatSolve_SeqSBAIJ_3_inplace;
187   C->ops->solvetranspose = MatSolve_SeqSBAIJ_3_inplace;
188   C->assembled = PETSC_TRUE;
189   C->preallocated = PETSC_TRUE;
190   ierr = PetscLogFlops(1.3333*27*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
191   PetscFunctionReturn(0);
192 }
193