xref: /petsc/src/mat/impls/baij/seq/baijsolvtran3.c (revision ccb4e88a40f0b86eaeca07ff64c64e4de2fae686)
1 #include <../src/mat/impls/baij/seq/baij.h>
2 #include <petsc/private/kernels/blockinvert.h>
3 
4 PetscErrorCode MatSolveTranspose_SeqBAIJ_3_inplace(Mat A,Vec bb,Vec xx)
5 {
6   Mat_SeqBAIJ       *a   =(Mat_SeqBAIJ*)A->data;
7   IS                iscol=a->col,isrow=a->row;
8   PetscErrorCode    ierr;
9   const PetscInt    *r,*c,*rout,*cout;
10   const PetscInt    *diag=a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
11   PetscInt          i,nz,idx,idt,ii,ic,ir,oidx;
12   const MatScalar   *aa=a->a,*v;
13   PetscScalar       s1,s2,s3,x1,x2,x3,*x,*t;
14   const PetscScalar *b;
15 
16   PetscFunctionBegin;
17   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
18   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
19   t    = a->solve_work;
20 
21   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
22   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
23 
24   /* copy the b into temp work space according to permutation */
25   ii = 0;
26   for (i=0; i<n; i++) {
27     ic      = 3*c[i];
28     t[ii]   = b[ic];
29     t[ii+1] = b[ic+1];
30     t[ii+2] = b[ic+2];
31     ii     += 3;
32   }
33 
34   /* forward solve the U^T */
35   idx = 0;
36   for (i=0; i<n; i++) {
37 
38     v = aa + 9*diag[i];
39     /* multiply by the inverse of the block diagonal */
40     x1 = t[idx];   x2 = t[1+idx]; x3    = t[2+idx];
41     s1 = v[0]*x1  +  v[1]*x2 +  v[2]*x3;
42     s2 = v[3]*x1  +  v[4]*x2 +  v[5]*x3;
43     s3 = v[6]*x1  +  v[7]*x2 + v[8]*x3;
44     v += 9;
45 
46     vi = aj + diag[i] + 1;
47     nz = ai[i+1] - diag[i] - 1;
48     while (nz--) {
49       oidx       = 3*(*vi++);
50       t[oidx]   -= v[0]*s1  +  v[1]*s2 +  v[2]*s3;
51       t[oidx+1] -= v[3]*s1  +  v[4]*s2 +  v[5]*s3;
52       t[oidx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
53       v         += 9;
54     }
55     t[idx] = s1;t[1+idx] = s2; t[2+idx] = s3;
56     idx   += 3;
57   }
58   /* backward solve the L^T */
59   for (i=n-1; i>=0; i--) {
60     v   = aa + 9*diag[i] - 9;
61     vi  = aj + diag[i] - 1;
62     nz  = diag[i] - ai[i];
63     idt = 3*i;
64     s1  = t[idt];  s2 = t[1+idt]; s3 = t[2+idt];
65     while (nz--) {
66       idx       = 3*(*vi--);
67       t[idx]   -=  v[0]*s1 +  v[1]*s2 +  v[2]*s3;
68       t[idx+1] -=  v[3]*s1 +  v[4]*s2 +  v[5]*s3;
69       t[idx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
70       v        -= 9;
71     }
72   }
73 
74   /* copy t into x according to permutation */
75   ii = 0;
76   for (i=0; i<n; i++) {
77     ir      = 3*r[i];
78     x[ir]   = t[ii];
79     x[ir+1] = t[ii+1];
80     x[ir+2] = t[ii+2];
81     ii     += 3;
82   }
83 
84   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
85   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
86   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
87   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
88   ierr = PetscLogFlops(2.0*9*(a->nz) - 3.0*A->cmap->n);CHKERRQ(ierr);
89   PetscFunctionReturn(0);
90 }
91 
92 PetscErrorCode MatSolveTranspose_SeqBAIJ_3(Mat A,Vec bb,Vec xx)
93 {
94   Mat_SeqBAIJ       *a=(Mat_SeqBAIJ*)A->data;
95   PetscErrorCode    ierr;
96   IS                iscol=a->col,isrow=a->row;
97   const PetscInt    n    =a->mbs,*vi,*ai=a->i,*aj=a->j,*diag=a->diag;
98   const PetscInt    *r,*c,*rout,*cout;
99   PetscInt          nz,idx,idt,j,i,oidx,ii,ic,ir;
100   const PetscInt    bs =A->rmap->bs,bs2=a->bs2;
101   const MatScalar   *aa=a->a,*v;
102   PetscScalar       s1,s2,s3,x1,x2,x3,*x,*t;
103   const PetscScalar *b;
104 
105   PetscFunctionBegin;
106   ierr = VecGetArrayRead(bb,&b);CHKERRQ(ierr);
107   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
108   t    = a->solve_work;
109 
110   ierr = ISGetIndices(isrow,&rout);CHKERRQ(ierr); r = rout;
111   ierr = ISGetIndices(iscol,&cout);CHKERRQ(ierr); c = cout;
112 
113   /* copy b into temp work space according to permutation */
114   for (i=0; i<n; i++) {
115     ii    = bs*i; ic = bs*c[i];
116     t[ii] = b[ic]; t[ii+1] = b[ic+1]; t[ii+2] = b[ic+2];
117   }
118 
119   /* forward solve the U^T */
120   idx = 0;
121   for (i=0; i<n; i++) {
122     v = aa + bs2*diag[i];
123     /* multiply by the inverse of the block diagonal */
124     x1 = t[idx];   x2 = t[1+idx]; x3    = t[2+idx];
125     s1 = v[0]*x1  +  v[1]*x2 +  v[2]*x3;
126     s2 = v[3]*x1  +  v[4]*x2 +  v[5]*x3;
127     s3 = v[6]*x1  +  v[7]*x2 + v[8]*x3;
128     v -= bs2;
129 
130     vi = aj + diag[i] - 1;
131     nz = diag[i] - diag[i+1] - 1;
132     for (j=0; j>-nz; j--) {
133       oidx       = bs*vi[j];
134       t[oidx]   -= v[0]*s1  +  v[1]*s2 +  v[2]*s3;
135       t[oidx+1] -= v[3]*s1  +  v[4]*s2 +  v[5]*s3;
136       t[oidx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
137       v         -= bs2;
138     }
139     t[idx] = s1;t[1+idx] = s2;  t[2+idx] = s3;
140     idx   += bs;
141   }
142   /* backward solve the L^T */
143   for (i=n-1; i>=0; i--) {
144     v   = aa + bs2*ai[i];
145     vi  = aj + ai[i];
146     nz  = ai[i+1] - ai[i];
147     idt = bs*i;
148     s1  = t[idt];  s2 = t[1+idt];  s3 = t[2+idt];
149     for (j=0; j<nz; j++) {
150       idx       = bs*vi[j];
151       t[idx]   -= v[0]*s1  +  v[1]*s2 +  v[2]*s3;
152       t[idx+1] -= v[3]*s1  +  v[4]*s2 +  v[5]*s3;
153       t[idx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
154       v        += bs2;
155     }
156   }
157 
158   /* copy t into x according to permutation */
159   for (i=0; i<n; i++) {
160     ii    = bs*i;  ir = bs*r[i];
161     x[ir] = t[ii];  x[ir+1] = t[ii+1]; x[ir+2] = t[ii+2];
162   }
163 
164   ierr = ISRestoreIndices(isrow,&rout);CHKERRQ(ierr);
165   ierr = ISRestoreIndices(iscol,&cout);CHKERRQ(ierr);
166   ierr = VecRestoreArrayRead(bb,&b);CHKERRQ(ierr);
167   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
168   ierr = PetscLogFlops(2.0*bs2*(a->nz) - bs*A->cmap->n);CHKERRQ(ierr);
169   PetscFunctionReturn(0);
170 }
171