xref: /petsc/src/mat/impls/sbaij/seq/sbaijfact5.c (revision f2a5309cf2bd60e875de7457ab3728dd4e42fdc5)
1 #include "sbaij.h"
2 #include "src/inline/ilu.h"
3 
4 /*
5       Version for when blocks are 4 by 4 Using natural ordering
6 */
7 #undef __FUNC__
8 #define __FUNC__ "MatCholeskyFactorNumeric_SeqSBAIJ_4_NaturalOrdering"
9 int MatCholeskyFactorNumeric_SeqSBAIJ_4_NaturalOrdering(Mat A,Mat *B)
10 {
11   Mat                C = *B;
12   Mat_SeqSBAIJ       *a = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ *)C->data;
13   int                ierr,i,j,mbs=a->mbs,*bi=b->i,*bj=b->j;
14   int                *ai,*aj,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 
18   PetscFunctionBegin;
19 
20   /* initialization */
21   ierr = PetscMalloc(16*mbs*sizeof(MatScalar),&rtmp);CHKERRQ(ierr);
22   ierr = PetscMemzero(rtmp,16*mbs*sizeof(MatScalar));CHKERRQ(ierr);
23   ierr = PetscMalloc(2*mbs*sizeof(int),&il);CHKERRQ(ierr);
24   jl   = il + mbs;
25   for (i=0; i<mbs; i++) {
26     jl[i] = mbs; il[0] = 0;
27   }
28   ierr = PetscMalloc(32*sizeof(MatScalar),&dk);CHKERRQ(ierr);
29   uik  = dk + 16;
30 
31   ai = a->i; aj = a->j; aa = a->a;
32 
33   /* for each row k */
34   for (k = 0; k<mbs; k++){
35 
36     /*initialize k-th row with elements nonzero in row k of A */
37     jmin = ai[k]; jmax = ai[k+1];
38     if (jmin < jmax) {
39       ap = aa + jmin*16;
40       for (j = jmin; j < jmax; j++){
41         vj = aj[j];         /* block col. index */
42         rtmp_ptr = rtmp + vj*16;
43         for (i=0; i<16; i++) *rtmp_ptr++ = *ap++;
44       }
45     }
46 
47     /* modify k-th row by adding in those rows i with U(i,k) != 0 */
48     ierr = PetscMemcpy(dk,rtmp+k*16,16*sizeof(MatScalar));CHKERRQ(ierr);
49     i = jl[k]; /* first row to be added to k_th row  */
50 
51     while (i < mbs){
52       nexti = jl[i]; /* next row to be added to k_th row */
53 
54       /* compute multiplier */
55       ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */
56 
57       /* uik = -inv(Di)*U_bar(i,k) */
58       diag = ba + i*16;
59       u    = ba + ili*16;
60 
61       uik[0] = -(diag[0]*u[0] + diag[4]*u[1] + diag[8]*u[2] + diag[12]*u[3]);
62       uik[1] = -(diag[1]*u[0] + diag[5]*u[1] + diag[9]*u[2] + diag[13]*u[3]);
63       uik[2] = -(diag[2]*u[0] + diag[6]*u[1] + diag[10]*u[2]+ diag[14]*u[3]);
64       uik[3] = -(diag[3]*u[0] + diag[7]*u[1] + diag[11]*u[2]+ diag[15]*u[3]);
65 
66       uik[4] = -(diag[0]*u[4] + diag[4]*u[5] + diag[8]*u[6] + diag[12]*u[7]);
67       uik[5] = -(diag[1]*u[4] + diag[5]*u[5] + diag[9]*u[6] + diag[13]*u[7]);
68       uik[6] = -(diag[2]*u[4] + diag[6]*u[5] + diag[10]*u[6]+ diag[14]*u[7]);
69       uik[7] = -(diag[3]*u[4] + diag[7]*u[5] + diag[11]*u[6]+ diag[15]*u[7]);
70 
71       uik[8] = -(diag[0]*u[8] + diag[4]*u[9] + diag[8]*u[10] + diag[12]*u[11]);
72       uik[9] = -(diag[1]*u[8] + diag[5]*u[9] + diag[9]*u[10] + diag[13]*u[11]);
73       uik[10]= -(diag[2]*u[8] + diag[6]*u[9] + diag[10]*u[10]+ diag[14]*u[11]);
74       uik[11]= -(diag[3]*u[8] + diag[7]*u[9] + diag[11]*u[10]+ diag[15]*u[11]);
75 
76       uik[12]= -(diag[0]*u[12] + diag[4]*u[13] + diag[8]*u[14] + diag[12]*u[15]);
77       uik[13]= -(diag[1]*u[12] + diag[5]*u[13] + diag[9]*u[14] + diag[13]*u[15]);
78       uik[14]= -(diag[2]*u[12] + diag[6]*u[13] + diag[10]*u[14]+ diag[14]*u[15]);
79       uik[15]= -(diag[3]*u[12] + diag[7]*u[13] + diag[11]*u[14]+ diag[15]*u[15]);
80 
81       /* update D(k) += -U(i,k)^T * U_bar(i,k) */
82       dk[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
83       dk[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
84       dk[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
85       dk[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];
86 
87       dk[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
88       dk[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
89       dk[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
90       dk[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];
91 
92       dk[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
93       dk[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
94       dk[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
95       dk[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];
96 
97       dk[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
98       dk[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
99       dk[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
100       dk[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];
101 
102       /* update -U(i,k) */
103       ierr = PetscMemcpy(ba+ili*16,uik,16*sizeof(MatScalar));CHKERRQ(ierr);
104 
105       /* add multiple of row i to k-th row ... */
106       jmin = ili + 1; jmax = bi[i+1];
107       if (jmin < jmax){
108         for (j=jmin; j<jmax; j++) {
109           /* rtmp += -U(i,k)^T * U_bar(i,j) */
110           rtmp_ptr = rtmp + bj[j]*16;
111           u = ba + j*16;
112           rtmp_ptr[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
113           rtmp_ptr[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
114           rtmp_ptr[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
115           rtmp_ptr[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];
116 
117           rtmp_ptr[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
118           rtmp_ptr[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
119           rtmp_ptr[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
120           rtmp_ptr[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];
121 
122           rtmp_ptr[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
123           rtmp_ptr[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
124           rtmp_ptr[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
125           rtmp_ptr[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];
126 
127           rtmp_ptr[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
128           rtmp_ptr[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
129           rtmp_ptr[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
130           rtmp_ptr[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];
131         }
132 
133         /* ... add i to row list for next nonzero entry */
134         il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
135         j     = bj[jmin];
136         jl[i] = jl[j]; jl[j] = i; /* update jl */
137       }
138       i = nexti;
139     }
140 
141     /* save nonzero entries in k-th row of U ... */
142 
143     /* invert diagonal block */
144     diag = ba+k*16;
145     ierr = PetscMemcpy(diag,dk,16*sizeof(MatScalar));CHKERRQ(ierr);
146     ierr = Kernel_A_gets_inverse_A_4(diag);CHKERRQ(ierr);
147 
148     jmin = bi[k]; jmax = bi[k+1];
149     if (jmin < jmax) {
150       for (j=jmin; j<jmax; j++){
151          vj = bj[j];           /* block col. index of U */
152          u   = ba + j*16;
153          rtmp_ptr = rtmp + vj*16;
154          for (k1=0; k1<16; k1++){
155            *u++        = *rtmp_ptr;
156            *rtmp_ptr++ = 0.0;
157          }
158       }
159 
160       /* ... add k to row list for first nonzero entry in k-th row */
161       il[k] = jmin;
162       i     = bj[jmin];
163       jl[k] = jl[i]; jl[i] = k;
164     }
165   }
166 
167   ierr = PetscFree(rtmp);CHKERRQ(ierr);
168   ierr = PetscFree(il);CHKERRQ(ierr);
169   ierr = PetscFree(dk);CHKERRQ(ierr);
170 
171   C->factor    = FACTOR_CHOLESKY;
172   C->assembled = PETSC_TRUE;
173   C->preallocated = PETSC_TRUE;
174   PetscLogFlops(1.3333*64*b->mbs); /* from inverting diagonal blocks */
175   PetscFunctionReturn(0);
176 }
177