Actual source code: baijsolvtrannat3.c

petsc-3.12.1 2019-10-22
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  1:  #include <../src/mat/impls/baij/seq/baij.h>

  3: PetscErrorCode MatSolveTranspose_SeqBAIJ_3_NaturalOrdering_inplace(Mat A,Vec bb,Vec xx)
  4: {
  5:   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
  6:   PetscErrorCode  ierr;
  7:   const PetscInt  n=a->mbs,*vi,*ai=a->i,*aj=a->j,*diag=a->diag;
  8:   PetscInt        i,nz,idx,idt,oidx;
  9:   const MatScalar *aa=a->a,*v;
 10:   PetscScalar     s1,s2,s3,x1,x2,x3,*x;

 13:   VecCopy(bb,xx);
 14:   VecGetArray(xx,&x);

 16:   /* forward solve the U^T */
 17:   idx = 0;
 18:   for (i=0; i<n; i++) {

 20:     v = aa + 9*diag[i];
 21:     /* multiply by the inverse of the block diagonal */
 22:     x1 = x[idx];   x2 = x[1+idx]; x3    = x[2+idx];
 23:     s1 = v[0]*x1  +  v[1]*x2 +  v[2]*x3;
 24:     s2 = v[3]*x1  +  v[4]*x2 +  v[5]*x3;
 25:     s3 = v[6]*x1  +  v[7]*x2 + v[8]*x3;
 26:     v += 9;

 28:     vi = aj + diag[i] + 1;
 29:     nz = ai[i+1] - diag[i] - 1;
 30:     while (nz--) {
 31:       oidx       = 3*(*vi++);
 32:       x[oidx]   -= v[0]*s1  +  v[1]*s2 +  v[2]*s3;
 33:       x[oidx+1] -= v[3]*s1  +  v[4]*s2 +  v[5]*s3;
 34:       x[oidx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
 35:       v         += 9;
 36:     }
 37:     x[idx] = s1;x[1+idx] = s2; x[2+idx] = s3;
 38:     idx   += 3;
 39:   }
 40:   /* backward solve the L^T */
 41:   for (i=n-1; i>=0; i--) {
 42:     v   = aa + 9*diag[i] - 9;
 43:     vi  = aj + diag[i] - 1;
 44:     nz  = diag[i] - ai[i];
 45:     idt = 3*i;
 46:     s1  = x[idt];  s2 = x[1+idt]; s3 = x[2+idt];
 47:     while (nz--) {
 48:       idx       = 3*(*vi--);
 49:       x[idx]   -=  v[0]*s1 +  v[1]*s2 +  v[2]*s3;
 50:       x[idx+1] -=  v[3]*s1 +  v[4]*s2 +  v[5]*s3;
 51:       x[idx+2] -= v[6]*s1 + v[7]*s2 + v[8]*s3;
 52:       v        -= 9;
 53:     }
 54:   }
 55:   VecRestoreArray(xx,&x);
 56:   PetscLogFlops(2.0*9.0*(a->nz) - 3.0*A->cmap->n);
 57:   return(0);
 58: }

 60: PetscErrorCode MatSolveTranspose_SeqBAIJ_3_NaturalOrdering(Mat A,Vec bb,Vec xx)
 61: {
 62:   Mat_SeqBAIJ     *a=(Mat_SeqBAIJ*)A->data;
 63:   PetscErrorCode  ierr;
 64:   const PetscInt  n=a->mbs,*vi,*ai=a->i,*aj=a->j,*diag=a->diag;
 65:   PetscInt        nz,idx,idt,j,i,oidx;
 66:   const PetscInt  bs =A->rmap->bs,bs2=a->bs2;
 67:   const MatScalar *aa=a->a,*v;
 68:   PetscScalar     s1,s2,s3,x1,x2,x3,*x;

 71:   VecCopy(bb,xx);
 72:   VecGetArray(xx,&x);

 74:   /* forward solve the U^T */
 75:   idx = 0;
 76:   for (i=0; i<n; i++) {
 77:     v = aa + bs2*diag[i];
 78:     /* multiply by the inverse of the block diagonal */
 79:     x1 = x[idx];   x2 = x[1+idx];  x3 = x[2+idx];
 80:     s1 = v[0]*x1  +  v[1]*x2  + v[2]*x3;
 81:     s2 = v[3]*x1  +  v[4]*x2  + v[5]*x3;
 82:     s3 = v[6]*x1  +  v[7]*x2  + v[8]*x3;
 83:     v -= bs2;

 85:     vi = aj + diag[i] - 1;
 86:     nz = diag[i] - diag[i+1] - 1;
 87:     for (j=0; j>-nz; j--) {
 88:       oidx       = bs*vi[j];
 89:       x[oidx]   -= v[0]*s1  +  v[1]*s2  + v[2]*s3;
 90:       x[oidx+1] -= v[3]*s1  +  v[4]*s2  + v[5]*s3;
 91:       x[oidx+2] -= v[6]*s1  +  v[7]*s2  + v[8]*s3;
 92:       v         -= bs2;
 93:     }
 94:     x[idx] = s1;x[1+idx] = s2;  x[2+idx] = s3;
 95:     idx   += bs;
 96:   }
 97:   /* backward solve the L^T */
 98:   for (i=n-1; i>=0; i--) {
 99:     v   = aa + bs2*ai[i];
100:     vi  = aj + ai[i];
101:     nz  = ai[i+1] - ai[i];
102:     idt = bs*i;
103:     s1  = x[idt];  s2 = x[1+idt];  s3 = x[2+idt];
104:     for (j=0; j<nz; j++) {
105:       idx       = bs*vi[j];
106:       x[idx]   -= v[0]*s1  +  v[1]*s2  + v[2]*s3;
107:       x[idx+1] -= v[3]*s1  +  v[4]*s2  + v[5]*s3;
108:       x[idx+2] -= v[6]*s1  +  v[7]*s2  + v[8]*s3;
109:       v        += bs2;
110:     }
111:   }
112:   VecRestoreArray(xx,&x);
113:   PetscLogFlops(2.0*bs2*(a->nz) - bs*A->cmap->n);
114:   return(0);
115: }