xref: /petsc/src/mat/impls/baij/seq/baijsolvtrannat4.c (revision ccb4e88a40f0b86eaeca07ff64c64e4de2fae686)
1 #include <../src/mat/impls/baij/seq/baij.h>
2 
3 PetscErrorCode MatSolveTranspose_SeqBAIJ_4_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
4 {
5   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
6   PetscErrorCode  ierr;
7   const PetscInt  *diag=a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
8   PetscInt        i,nz,idx,idt,oidx;
9   const MatScalar *aa=a->a,*v;
10   PetscScalar     s1,s2,s3,s4,x1,x2,x3,x4,*x;
11 
12   PetscFunctionBegin;
13   ierr = VecCopy(bb,xx);CHKERRQ(ierr);
14   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
15 
16   /* forward solve the U^T */
17   idx = 0;
18   for (i=0; i<n; i++) {
19 
20     v = aa + 16*diag[i];
21     /* multiply by the inverse of the block diagonal */
22     x1 = x[idx];   x2 = x[1+idx]; x3    = x[2+idx]; x4 = x[3+idx];
23     s1 = v[0]*x1  +  v[1]*x2 +  v[2]*x3 +  v[3]*x4;
24     s2 = v[4]*x1  +  v[5]*x2 +  v[6]*x3 +  v[7]*x4;
25     s3 = v[8]*x1  +  v[9]*x2 + v[10]*x3 + v[11]*x4;
26     s4 = v[12]*x1 + v[13]*x2 + v[14]*x3 + v[15]*x4;
27     v += 16;
28 
29     vi = aj + diag[i] + 1;
30     nz = ai[i+1] - diag[i] - 1;
31     while (nz--) {
32       oidx       = 4*(*vi++);
33       x[oidx]   -= v[0]*s1  +  v[1]*s2 +  v[2]*s3 +  v[3]*s4;
34       x[oidx+1] -= v[4]*s1  +  v[5]*s2 +  v[6]*s3 +  v[7]*s4;
35       x[oidx+2] -= v[8]*s1 + v[9]*s2 + v[10]*s3 + v[11]*s4;
36       x[oidx+3] -= v[12]*s1 + v[13]*s2 + v[14]*s3 + v[15]*s4;
37       v         += 16;
38     }
39     x[idx] = s1;x[1+idx] = s2; x[2+idx] = s3;x[3+idx] = s4;
40     idx   += 4;
41   }
42   /* backward solve the L^T */
43   for (i=n-1; i>=0; i--) {
44     v   = aa + 16*diag[i] - 16;
45     vi  = aj + diag[i] - 1;
46     nz  = diag[i] - ai[i];
47     idt = 4*i;
48     s1  = x[idt];  s2 = x[1+idt]; s3 = x[2+idt];s4 = x[3+idt];
49     while (nz--) {
50       idx       = 4*(*vi--);
51       x[idx]   -=  v[0]*s1 +  v[1]*s2 +  v[2]*s3 +  v[3]*s4;
52       x[idx+1] -=  v[4]*s1 +  v[5]*s2 +  v[6]*s3 +  v[7]*s4;
53       x[idx+2] -= v[8]*s1 + v[9]*s2 + v[10]*s3 + v[11]*s4;
54       x[idx+3] -= v[12]*s1 + v[13]*s2 + v[14]*s3 + v[15]*s4;
55       v        -= 16;
56     }
57   }
58   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
59   ierr = PetscLogFlops(2.0*16*(a->nz) - 4.0*A->cmap->n);CHKERRQ(ierr);
60   PetscFunctionReturn(0);
61 }
62 
63 PetscErrorCode MatSolveTranspose_SeqBAIJ_4_NaturalOrdering(Mat A,Vec bb,Vec xx)
64 {
65   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
66   PetscErrorCode  ierr;
67   const PetscInt  n=a->mbs,*vi,*ai=a->i,*aj=a->j,*diag=a->diag;
68   PetscInt        nz,idx,idt,j,i,oidx;
69   const PetscInt  bs =A->rmap->bs,bs2=a->bs2;
70   const MatScalar *aa=a->a,*v;
71   PetscScalar     s1,s2,s3,s4,x1,x2,x3,x4,*x;
72 
73   PetscFunctionBegin;
74   ierr = VecCopy(bb,xx);CHKERRQ(ierr);
75   ierr = VecGetArray(xx,&x);CHKERRQ(ierr);
76 
77   /* forward solve the U^T */
78   idx = 0;
79   for (i=0; i<n; i++) {
80     v = aa + bs2*diag[i];
81     /* multiply by the inverse of the block diagonal */
82     x1 = x[idx];   x2 = x[1+idx];  x3 = x[2+idx];  x4 = x[3+idx];
83     s1 =  v[0]*x1  +  v[1]*x2  + v[2]*x3  + v[3]*x4;
84     s2 =  v[4]*x1  +  v[5]*x2  + v[6]*x3  + v[7]*x4;
85     s3 =  v[8]*x1  +  v[9]*x2  + v[10]*x3 + v[11]*x4;
86     s4 =  v[12]*x1 +  v[13]*x2 + v[14]*x3 + v[15]*x4;
87     v -= bs2;
88 
89     vi = aj + diag[i] - 1;
90     nz = diag[i] - diag[i+1] - 1;
91     for (j=0; j>-nz; j--) {
92       oidx       = bs*vi[j];
93       x[oidx]   -=  v[0]*s1  +  v[1]*s2  + v[2]*s3  + v[3]*s4;
94       x[oidx+1] -=  v[4]*s1  +  v[5]*s2  + v[6]*s3  + v[7]*s4;
95       x[oidx+2] -=  v[8]*s1  +  v[9]*s2  + v[10]*s3 + v[11]*s4;
96       x[oidx+3] -=  v[12]*s1 +  v[13]*s2 + v[14]*s3 + v[15]*s4;
97       v         -= bs2;
98     }
99     x[idx] = s1;x[1+idx] = s2;  x[2+idx] = s3;  x[3+idx] = s4;
100     idx   += bs;
101   }
102   /* backward solve the L^T */
103   for (i=n-1; i>=0; i--) {
104     v   = aa + bs2*ai[i];
105     vi  = aj + ai[i];
106     nz  = ai[i+1] - ai[i];
107     idt = bs*i;
108     s1  = x[idt];  s2 = x[1+idt];  s3 = x[2+idt];  s4 = x[3+idt];
109     for (j=0; j<nz; j++) {
110       idx       = bs*vi[j];
111       x[idx]   -=  v[0]*s1  +  v[1]*s2  + v[2]*s3  + v[3]*s4;
112       x[idx+1] -=  v[4]*s1  +  v[5]*s2  + v[6]*s3  + v[7]*s4;
113       x[idx+2] -=  v[8]*s1  +  v[9]*s2  + v[10]*s3 + v[11]*s4;
114       x[idx+3] -=  v[12]*s1 +  v[13]*s2 + v[14]*s3 + v[15]*s4;
115       v        += bs2;
116     }
117   }
118   ierr = VecRestoreArray(xx,&x);CHKERRQ(ierr);
119   ierr = PetscLogFlops(2.0*bs2*(a->nz) - bs*A->cmap->n);CHKERRQ(ierr);
120   PetscFunctionReturn(0);
121 }
122