Actual source code: baijsolvtran2.c

petsc-master 2019-12-10
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  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:   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,x1,x2,*x,*t;
 14:   const PetscScalar *b;

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

 21:   ISGetIndices(isrow,&rout); r = rout;
 22:   ISGetIndices(iscol,&cout); c = cout;

 24:   /* copy the b into temp work space according to permutation */
 25:   ii = 0;
 26:   for (i=0; i<n; i++) {
 27:     ic      = 2*c[i];
 28:     t[ii]   = b[ic];
 29:     t[ii+1] = b[ic+1];
 30:     ii     += 2;
 31:   }

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

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

 44:     vi = aj + diag[i] + 1;
 45:     nz = ai[i+1] - diag[i] - 1;
 46:     while (nz--) {
 47:       oidx       = 2*(*vi++);
 48:       t[oidx]   -= v[0]*s1  +  v[1]*s2;
 49:       t[oidx+1] -= v[2]*s1  +  v[3]*s2;
 50:       v         += 4;
 51:     }
 52:     t[idx] = s1;t[1+idx] = s2;
 53:     idx   += 2;
 54:   }
 55:   /* backward solve the L^T */
 56:   for (i=n-1; i>=0; i--) {
 57:     v   = aa + 4*diag[i] - 4;
 58:     vi  = aj + diag[i] - 1;
 59:     nz  = diag[i] - ai[i];
 60:     idt = 2*i;
 61:     s1  = t[idt];  s2 = t[1+idt];
 62:     while (nz--) {
 63:       idx       = 2*(*vi--);
 64:       t[idx]   -=  v[0]*s1 +  v[1]*s2;
 65:       t[idx+1] -=  v[2]*s1 +  v[3]*s2;
 66:       v        -= 4;
 67:     }
 68:   }

 70:   /* copy t into x according to permutation */
 71:   ii = 0;
 72:   for (i=0; i<n; i++) {
 73:     ir      = 2*r[i];
 74:     x[ir]   = t[ii];
 75:     x[ir+1] = t[ii+1];
 76:     ii     += 2;
 77:   }

 79:   ISRestoreIndices(isrow,&rout);
 80:   ISRestoreIndices(iscol,&cout);
 81:   VecRestoreArrayRead(bb,&b);
 82:   VecRestoreArray(xx,&x);
 83:   PetscLogFlops(2.0*4*(a->nz) - 2.0*A->cmap->n);
 84:   return(0);
 85: }

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

101:   VecGetArrayRead(bb,&b);
102:   VecGetArray(xx,&x);
103:   t    = a->solve_work;

105:   ISGetIndices(isrow,&rout); r = rout;
106:   ISGetIndices(iscol,&cout); c = cout;

108:   /* copy b into temp work space according to permutation */
109:   for (i=0; i<n; i++) {
110:     ii    = bs*i; ic = bs*c[i];
111:     t[ii] = b[ic]; t[ii+1] = b[ic+1];
112:   }

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

124:     vi = aj + diag[i] - 1;
125:     nz = diag[i] - diag[i+1] - 1;
126:     for (j=0; j>-nz; j--) {
127:       oidx       = bs*vi[j];
128:       t[oidx]   -= v[0]*s1  +  v[1]*s2;
129:       t[oidx+1] -= v[2]*s1  +  v[3]*s2;
130:       v         -= bs2;
131:     }
132:     t[idx] = s1;t[1+idx] = s2;
133:     idx   += bs;
134:   }
135:   /* backward solve the L^T */
136:   for (i=n-1; i>=0; i--) {
137:     v   = aa + bs2*ai[i];
138:     vi  = aj + ai[i];
139:     nz  = ai[i+1] - ai[i];
140:     idt = bs*i;
141:     s1  = t[idt];  s2 = t[1+idt];
142:     for (j=0; j<nz; j++) {
143:       idx       = bs*vi[j];
144:       t[idx]   -=  v[0]*s1 +  v[1]*s2;
145:       t[idx+1] -=  v[2]*s1 +  v[3]*s2;
146:       v        += bs2;
147:     }
148:   }

150:   /* copy t into x according to permutation */
151:   for (i=0; i<n; i++) {
152:     ii    = bs*i;  ir = bs*r[i];
153:     x[ir] = t[ii];  x[ir+1] = t[ii+1];
154:   }

156:   ISRestoreIndices(isrow,&rout);
157:   ISRestoreIndices(iscol,&cout);
158:   VecRestoreArrayRead(bb,&b);
159:   VecRestoreArray(xx,&x);
160:   PetscLogFlops(2.0*bs2*(a->nz) - bs*A->cmap->n);
161:   return(0);
162: }