Actual source code: baijsolvtran2.c

  1: #include <../src/mat/impls/baij/seq/baij.h>
  2: #include <petsc/private/kernels/blockinvert.h>

  4: PetscErrorCode MatSolveTranspose_SeqBAIJ_2_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:   const PetscInt    *r,*c,*rout,*cout;
  9:   const PetscInt    *diag=a->diag,n=a->mbs,*vi,*ai=a->i,*aj=a->j;
 10:   PetscInt          i,nz,idx,idt,ii,ic,ir,oidx;
 11:   const MatScalar   *aa=a->a,*v;
 12:   PetscScalar       s1,s2,x1,x2,*x,*t;
 13:   const PetscScalar *b;

 15:   VecGetArrayRead(bb,&b);
 16:   VecGetArray(xx,&x);
 17:   t    = a->solve_work;

 19:   ISGetIndices(isrow,&rout); r = rout;
 20:   ISGetIndices(iscol,&cout); c = cout;

 22:   /* copy the b into temp work space according to permutation */
 23:   ii = 0;
 24:   for (i=0; i<n; i++) {
 25:     ic      = 2*c[i];
 26:     t[ii]   = b[ic];
 27:     t[ii+1] = b[ic+1];
 28:     ii     += 2;
 29:   }

 31:   /* forward solve the U^T */
 32:   idx = 0;
 33:   for (i=0; i<n; i++) {

 35:     v = aa + 4*diag[i];
 36:     /* multiply by the inverse of the block diagonal */
 37:     x1 = t[idx];   x2 = t[1+idx];
 38:     s1 = v[0]*x1  +  v[1]*x2;
 39:     s2 = v[2]*x1  +  v[3]*x2;
 40:     v += 4;

 42:     vi = aj + diag[i] + 1;
 43:     nz = ai[i+1] - diag[i] - 1;
 44:     while (nz--) {
 45:       oidx       = 2*(*vi++);
 46:       t[oidx]   -= v[0]*s1  +  v[1]*s2;
 47:       t[oidx+1] -= v[2]*s1  +  v[3]*s2;
 48:       v         += 4;
 49:     }
 50:     t[idx] = s1;t[1+idx] = s2;
 51:     idx   += 2;
 52:   }
 53:   /* backward solve the L^T */
 54:   for (i=n-1; i>=0; i--) {
 55:     v   = aa + 4*diag[i] - 4;
 56:     vi  = aj + diag[i] - 1;
 57:     nz  = diag[i] - ai[i];
 58:     idt = 2*i;
 59:     s1  = t[idt];  s2 = t[1+idt];
 60:     while (nz--) {
 61:       idx       = 2*(*vi--);
 62:       t[idx]   -=  v[0]*s1 +  v[1]*s2;
 63:       t[idx+1] -=  v[2]*s1 +  v[3]*s2;
 64:       v        -= 4;
 65:     }
 66:   }

 68:   /* copy t into x according to permutation */
 69:   ii = 0;
 70:   for (i=0; i<n; i++) {
 71:     ir      = 2*r[i];
 72:     x[ir]   = t[ii];
 73:     x[ir+1] = t[ii+1];
 74:     ii     += 2;
 75:   }

 77:   ISRestoreIndices(isrow,&rout);
 78:   ISRestoreIndices(iscol,&cout);
 79:   VecRestoreArrayRead(bb,&b);
 80:   VecRestoreArray(xx,&x);
 81:   PetscLogFlops(2.0*4*(a->nz) - 2.0*A->cmap->n);
 82:   return 0;
 83: }

 85: PetscErrorCode MatSolveTranspose_SeqBAIJ_2(Mat A,Vec bb,Vec xx)
 86: {
 87:   Mat_SeqBAIJ       *a=(Mat_SeqBAIJ*)A->data;
 88:   IS                iscol=a->col,isrow=a->row;
 89:   const PetscInt    n    =a->mbs,*vi,*ai=a->i,*aj=a->j,*diag=a->diag;
 90:   const PetscInt    *r,*c,*rout,*cout;
 91:   PetscInt          nz,idx,idt,j,i,oidx,ii,ic,ir;
 92:   const PetscInt    bs =A->rmap->bs,bs2=a->bs2;
 93:   const MatScalar   *aa=a->a,*v;
 94:   PetscScalar       s1,s2,x1,x2,*x,*t;
 95:   const PetscScalar *b;

 97:   VecGetArrayRead(bb,&b);
 98:   VecGetArray(xx,&x);
 99:   t    = a->solve_work;

101:   ISGetIndices(isrow,&rout); r = rout;
102:   ISGetIndices(iscol,&cout); c = cout;

104:   /* copy b into temp work space according to permutation */
105:   for (i=0; i<n; i++) {
106:     ii    = bs*i; ic = bs*c[i];
107:     t[ii] = b[ic]; t[ii+1] = b[ic+1];
108:   }

110:   /* forward solve the U^T */
111:   idx = 0;
112:   for (i=0; i<n; i++) {
113:     v = aa + bs2*diag[i];
114:     /* multiply by the inverse of the block diagonal */
115:     x1 = t[idx];   x2 = t[1+idx];
116:     s1 = v[0]*x1  +  v[1]*x2;
117:     s2 = v[2]*x1  +  v[3]*x2;
118:     v -= bs2;

120:     vi = aj + diag[i] - 1;
121:     nz = diag[i] - diag[i+1] - 1;
122:     for (j=0; j>-nz; j--) {
123:       oidx       = bs*vi[j];
124:       t[oidx]   -= v[0]*s1  +  v[1]*s2;
125:       t[oidx+1] -= v[2]*s1  +  v[3]*s2;
126:       v         -= bs2;
127:     }
128:     t[idx] = s1;t[1+idx] = s2;
129:     idx   += bs;
130:   }
131:   /* backward solve the L^T */
132:   for (i=n-1; i>=0; i--) {
133:     v   = aa + bs2*ai[i];
134:     vi  = aj + ai[i];
135:     nz  = ai[i+1] - ai[i];
136:     idt = bs*i;
137:     s1  = t[idt];  s2 = t[1+idt];
138:     for (j=0; j<nz; j++) {
139:       idx       = bs*vi[j];
140:       t[idx]   -=  v[0]*s1 +  v[1]*s2;
141:       t[idx+1] -=  v[2]*s1 +  v[3]*s2;
142:       v        += bs2;
143:     }
144:   }

146:   /* copy t into x according to permutation */
147:   for (i=0; i<n; i++) {
148:     ii    = bs*i;  ir = bs*r[i];
149:     x[ir] = t[ii];  x[ir+1] = t[ii+1];
150:   }

152:   ISRestoreIndices(isrow,&rout);
153:   ISRestoreIndices(iscol,&cout);
154:   VecRestoreArrayRead(bb,&b);
155:   VecRestoreArray(xx,&x);
156:   PetscLogFlops(2.0*bs2*(a->nz) - bs*A->cmap->n);
157:   return 0;
158: }