Example #1
0
/* Version for when blocks are 4 by 4  */
PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_4(Mat C,Mat A,const MatFactorInfo *info)
{
  Mat_SeqSBAIJ   *a   = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ*)C->data;
  IS             perm = b->row;
  PetscErrorCode ierr;
  const PetscInt *ai,*aj,*perm_ptr,mbs=a->mbs,*bi=b->i,*bj=b->j;
  PetscInt       i,j,*a2anew,k,k1,jmin,jmax,*jl,*il,vj,nexti,ili;
  MatScalar      *ba = b->a,*aa,*ap,*dk,*uik;
  MatScalar      *u,*diag,*rtmp,*rtmp_ptr;
  PetscBool      pivotinblocks = b->pivotinblocks;
  PetscReal      shift         = info->shiftamount;
  PetscBool      allowzeropivot,zeropivotdetected=PETSC_FALSE;

  PetscFunctionBegin;
  /* initialization */
  allowzeropivot = PetscNot(A->erroriffailure);
  ierr = PetscCalloc1(16*mbs,&rtmp);CHKERRQ(ierr);
  ierr = PetscMalloc2(mbs,&il,mbs,&jl);CHKERRQ(ierr);
  il[0] = 0;
  for (i=0; i<mbs; i++) jl[i] = mbs; 
  
  ierr = PetscMalloc2(16,&dk,16,&uik);CHKERRQ(ierr);
  ierr = ISGetIndices(perm,&perm_ptr);CHKERRQ(ierr);

  /* check permutation */
  if (!a->permute) {
    ai = a->i; aj = a->j; aa = a->a;
  } else {
    ai   = a->inew; aj = a->jnew;
    ierr = PetscMalloc1(16*ai[mbs],&aa);CHKERRQ(ierr);
    ierr = PetscMemcpy(aa,a->a,16*ai[mbs]*sizeof(MatScalar));CHKERRQ(ierr);
    ierr = PetscMalloc1(ai[mbs],&a2anew);CHKERRQ(ierr);
    ierr = PetscMemcpy(a2anew,a->a2anew,(ai[mbs])*sizeof(PetscInt));CHKERRQ(ierr);

    for (i=0; i<mbs; i++) {
      jmin = ai[i]; jmax = ai[i+1];
      for (j=jmin; j<jmax; j++) {
        while (a2anew[j] != j) {
          k = a2anew[j]; a2anew[j] = a2anew[k]; a2anew[k] = k;
          for (k1=0; k1<16; k1++) {
            dk[k1]      = aa[k*16+k1];
            aa[k*16+k1] = aa[j*16+k1];
            aa[j*16+k1] = dk[k1];
          }
        }
        /* transform columnoriented blocks that lie in the lower triangle to roworiented blocks */
        if (i > aj[j]) {
          /* printf("change orientation, row: %d, col: %d\n",i,aj[j]); */
          ap = aa + j*16;                     /* ptr to the beginning of j-th block of aa */
          for (k=0; k<16; k++) dk[k] = ap[k]; /* dk <- j-th block of aa */
          for (k=0; k<4; k++) {               /* j-th block of aa <- dk^T */
            for (k1=0; k1<4; k1++) *ap++ = dk[k + 4*k1];
          }
        }
      }
    }
    ierr = PetscFree(a2anew);CHKERRQ(ierr);
  }

  /* for each row k */
  for (k = 0; k<mbs; k++) {

    /*initialize k-th row with elements nonzero in row perm(k) of A */
    jmin = ai[perm_ptr[k]]; jmax = ai[perm_ptr[k]+1];
    if (jmin < jmax) {
      ap = aa + jmin*16;
      for (j = jmin; j < jmax; j++) {
        vj       = perm_ptr[aj[j]];   /* block col. index */
        rtmp_ptr = rtmp + vj*16;
        for (i=0; i<16; i++) *rtmp_ptr++ = *ap++;
      }
    }

    /* modify k-th row by adding in those rows i with U(i,k) != 0 */
    ierr = PetscMemcpy(dk,rtmp+k*16,16*sizeof(MatScalar));CHKERRQ(ierr);
    i    = jl[k]; /* first row to be added to k_th row  */

    while (i < mbs) {
      nexti = jl[i]; /* next row to be added to k_th row */

      /* compute multiplier */
      ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */

      /* uik = -inv(Di)*U_bar(i,k) */
      diag = ba + i*16;
      u    = ba + ili*16;

      uik[0] = -(diag[0]*u[0] + diag[4]*u[1] + diag[8]*u[2] + diag[12]*u[3]);
      uik[1] = -(diag[1]*u[0] + diag[5]*u[1] + diag[9]*u[2] + diag[13]*u[3]);
      uik[2] = -(diag[2]*u[0] + diag[6]*u[1] + diag[10]*u[2]+ diag[14]*u[3]);
      uik[3] = -(diag[3]*u[0] + diag[7]*u[1] + diag[11]*u[2]+ diag[15]*u[3]);

      uik[4] = -(diag[0]*u[4] + diag[4]*u[5] + diag[8]*u[6] + diag[12]*u[7]);
      uik[5] = -(diag[1]*u[4] + diag[5]*u[5] + diag[9]*u[6] + diag[13]*u[7]);
      uik[6] = -(diag[2]*u[4] + diag[6]*u[5] + diag[10]*u[6]+ diag[14]*u[7]);
      uik[7] = -(diag[3]*u[4] + diag[7]*u[5] + diag[11]*u[6]+ diag[15]*u[7]);

      uik[8] = -(diag[0]*u[8] + diag[4]*u[9] + diag[8]*u[10] + diag[12]*u[11]);
      uik[9] = -(diag[1]*u[8] + diag[5]*u[9] + diag[9]*u[10] + diag[13]*u[11]);
      uik[10]= -(diag[2]*u[8] + diag[6]*u[9] + diag[10]*u[10]+ diag[14]*u[11]);
      uik[11]= -(diag[3]*u[8] + diag[7]*u[9] + diag[11]*u[10]+ diag[15]*u[11]);

      uik[12]= -(diag[0]*u[12] + diag[4]*u[13] + diag[8]*u[14] + diag[12]*u[15]);
      uik[13]= -(diag[1]*u[12] + diag[5]*u[13] + diag[9]*u[14] + diag[13]*u[15]);
      uik[14]= -(diag[2]*u[12] + diag[6]*u[13] + diag[10]*u[14]+ diag[14]*u[15]);
      uik[15]= -(diag[3]*u[12] + diag[7]*u[13] + diag[11]*u[14]+ diag[15]*u[15]);

      /* update D(k) += -U(i,k)^T * U_bar(i,k) */
      dk[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
      dk[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
      dk[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
      dk[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];

      dk[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
      dk[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
      dk[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
      dk[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];

      dk[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
      dk[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
      dk[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
      dk[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];

      dk[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
      dk[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
      dk[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
      dk[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];

      ierr = PetscLogFlops(64.0*4.0);CHKERRQ(ierr);

      /* update -U(i,k) */
      ierr = PetscMemcpy(ba+ili*16,uik,16*sizeof(MatScalar));CHKERRQ(ierr);

      /* add multiple of row i to k-th row ... */
      jmin = ili + 1; jmax = bi[i+1];
      if (jmin < jmax) {
        for (j=jmin; j<jmax; j++) {
          /* rtmp += -U(i,k)^T * U_bar(i,j) */
          rtmp_ptr     = rtmp + bj[j]*16;
          u            = ba + j*16;
          rtmp_ptr[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
          rtmp_ptr[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
          rtmp_ptr[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
          rtmp_ptr[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];

          rtmp_ptr[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
          rtmp_ptr[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
          rtmp_ptr[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
          rtmp_ptr[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];

          rtmp_ptr[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
          rtmp_ptr[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
          rtmp_ptr[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
          rtmp_ptr[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];

          rtmp_ptr[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
          rtmp_ptr[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
          rtmp_ptr[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
          rtmp_ptr[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];
        }
        ierr = PetscLogFlops(2.0*64.0*(jmax-jmin));CHKERRQ(ierr);

        /* ... add i to row list for next nonzero entry */
        il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
        j     = bj[jmin];
        jl[i] = jl[j]; jl[j] = i; /* update jl */
      }
      i = nexti;
    }

    /* save nonzero entries in k-th row of U ... */

    /* invert diagonal block */
    diag = ba+k*16;
    ierr = PetscMemcpy(diag,dk,16*sizeof(MatScalar));CHKERRQ(ierr);

    if (pivotinblocks) {
      ierr = PetscKernel_A_gets_inverse_A_4(diag,shift, allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
      if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
    } else {
      ierr = PetscKernel_A_gets_inverse_A_4_nopivot(diag);CHKERRQ(ierr);
    }

    jmin = bi[k]; jmax = bi[k+1];
    if (jmin < jmax) {
      for (j=jmin; j<jmax; j++) {
        vj       = bj[j];      /* block col. index of U */
        u        = ba + j*16;
        rtmp_ptr = rtmp + vj*16;
        for (k1=0; k1<16; k1++) {
          *u++        = *rtmp_ptr;
          *rtmp_ptr++ = 0.0;
        }
      }

      /* ... add k to row list for first nonzero entry in k-th row */
      il[k] = jmin;
      i     = bj[jmin];
      jl[k] = jl[i]; jl[i] = k;
    }
  }

  ierr = PetscFree(rtmp);CHKERRQ(ierr);
  ierr = PetscFree2(il,jl);CHKERRQ(ierr);
  ierr = PetscFree2(dk,uik);CHKERRQ(ierr);
  if (a->permute) {
    ierr = PetscFree(aa);CHKERRQ(ierr);
  }

  ierr = ISRestoreIndices(perm,&perm_ptr);CHKERRQ(ierr);

  C->ops->solve          = MatSolve_SeqSBAIJ_4_inplace;
  C->ops->solvetranspose = MatSolve_SeqSBAIJ_4_inplace;
  C->assembled           = PETSC_TRUE;
  C->preallocated        = PETSC_TRUE;

  ierr = PetscLogFlops(1.3333*64*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
  PetscFunctionReturn(0);
}
Example #2
0
PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_4_NaturalOrdering(Mat C,Mat A,const MatFactorInfo *info)
{
  Mat_SeqSBAIJ   *a = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ*)C->data;
  PetscErrorCode ierr;
  PetscInt       i,j,mbs=a->mbs,*bi=b->i,*bj=b->j;
  PetscInt       *ai,*aj,k,k1,jmin,jmax,*jl,*il,vj,nexti,ili;
  MatScalar      *ba = b->a,*aa,*ap,*dk,*uik;
  MatScalar      *u,*diag,*rtmp,*rtmp_ptr;
  PetscBool      pivotinblocks = b->pivotinblocks; 
  PetscReal      shift         = info->shiftamount;
  PetscBool      allowzeropivot,zeropivotdetected=PETSC_FALSE;

  PetscFunctionBegin;
  /* initialization */
  allowzeropivot = PetscNot(A->erroriffailure);
  ierr = PetscCalloc1(16*mbs,&rtmp);CHKERRQ(ierr);
  ierr = PetscMalloc2(mbs,&il,mbs,&jl);CHKERRQ(ierr);
  for (i=0; i<mbs; i++) {
    jl[i] = mbs; il[0] = 0;
  }
  ierr = PetscMalloc2(16,&dk,16,&uik);CHKERRQ(ierr);
  ai   = a->i; aj = a->j; aa = a->a;

  /* for each row k */
  for (k = 0; k<mbs; k++) {

    /*initialize k-th row with elements nonzero in row k of A */
    jmin = ai[k]; jmax = ai[k+1];
    if (jmin < jmax) {
      ap = aa + jmin*16;
      for (j = jmin; j < jmax; j++) {
        vj       = aj[j];   /* block col. index */
        rtmp_ptr = rtmp + vj*16;
        for (i=0; i<16; i++) *rtmp_ptr++ = *ap++;
      }
    }

    /* modify k-th row by adding in those rows i with U(i,k) != 0 */
    ierr = PetscMemcpy(dk,rtmp+k*16,16*sizeof(MatScalar));CHKERRQ(ierr);
    i    = jl[k]; /* first row to be added to k_th row  */

    while (i < mbs) {
      nexti = jl[i]; /* next row to be added to k_th row */

      /* compute multiplier */
      ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */

      /* uik = -inv(Di)*U_bar(i,k) */
      diag = ba + i*16;
      u    = ba + ili*16;

      uik[0] = -(diag[0]*u[0] + diag[4]*u[1] + diag[8]*u[2] + diag[12]*u[3]);
      uik[1] = -(diag[1]*u[0] + diag[5]*u[1] + diag[9]*u[2] + diag[13]*u[3]);
      uik[2] = -(diag[2]*u[0] + diag[6]*u[1] + diag[10]*u[2]+ diag[14]*u[3]);
      uik[3] = -(diag[3]*u[0] + diag[7]*u[1] + diag[11]*u[2]+ diag[15]*u[3]);

      uik[4] = -(diag[0]*u[4] + diag[4]*u[5] + diag[8]*u[6] + diag[12]*u[7]);
      uik[5] = -(diag[1]*u[4] + diag[5]*u[5] + diag[9]*u[6] + diag[13]*u[7]);
      uik[6] = -(diag[2]*u[4] + diag[6]*u[5] + diag[10]*u[6]+ diag[14]*u[7]);
      uik[7] = -(diag[3]*u[4] + diag[7]*u[5] + diag[11]*u[6]+ diag[15]*u[7]);

      uik[8] = -(diag[0]*u[8] + diag[4]*u[9] + diag[8]*u[10] + diag[12]*u[11]);
      uik[9] = -(diag[1]*u[8] + diag[5]*u[9] + diag[9]*u[10] + diag[13]*u[11]);
      uik[10]= -(diag[2]*u[8] + diag[6]*u[9] + diag[10]*u[10]+ diag[14]*u[11]);
      uik[11]= -(diag[3]*u[8] + diag[7]*u[9] + diag[11]*u[10]+ diag[15]*u[11]);

      uik[12]= -(diag[0]*u[12] + diag[4]*u[13] + diag[8]*u[14] + diag[12]*u[15]);
      uik[13]= -(diag[1]*u[12] + diag[5]*u[13] + diag[9]*u[14] + diag[13]*u[15]);
      uik[14]= -(diag[2]*u[12] + diag[6]*u[13] + diag[10]*u[14]+ diag[14]*u[15]);
      uik[15]= -(diag[3]*u[12] + diag[7]*u[13] + diag[11]*u[14]+ diag[15]*u[15]);

      /* update D(k) += -U(i,k)^T * U_bar(i,k) */
      dk[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
      dk[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
      dk[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
      dk[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];

      dk[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
      dk[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
      dk[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
      dk[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];

      dk[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
      dk[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
      dk[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
      dk[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];

      dk[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
      dk[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
      dk[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
      dk[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];

      ierr = PetscLogFlops(64.0*4.0);CHKERRQ(ierr);

      /* update -U(i,k) */
      ierr = PetscMemcpy(ba+ili*16,uik,16*sizeof(MatScalar));CHKERRQ(ierr);

      /* add multiple of row i to k-th row ... */
      jmin = ili + 1; jmax = bi[i+1];
      if (jmin < jmax) {
        for (j=jmin; j<jmax; j++) {
          /* rtmp += -U(i,k)^T * U_bar(i,j) */
          rtmp_ptr     = rtmp + bj[j]*16;
          u            = ba + j*16;
          rtmp_ptr[0] += uik[0]*u[0] + uik[1]*u[1] + uik[2]*u[2] + uik[3]*u[3];
          rtmp_ptr[1] += uik[4]*u[0] + uik[5]*u[1] + uik[6]*u[2] + uik[7]*u[3];
          rtmp_ptr[2] += uik[8]*u[0] + uik[9]*u[1] + uik[10]*u[2]+ uik[11]*u[3];
          rtmp_ptr[3] += uik[12]*u[0]+ uik[13]*u[1]+ uik[14]*u[2]+ uik[15]*u[3];

          rtmp_ptr[4] += uik[0]*u[4] + uik[1]*u[5] + uik[2]*u[6] + uik[3]*u[7];
          rtmp_ptr[5] += uik[4]*u[4] + uik[5]*u[5] + uik[6]*u[6] + uik[7]*u[7];
          rtmp_ptr[6] += uik[8]*u[4] + uik[9]*u[5] + uik[10]*u[6]+ uik[11]*u[7];
          rtmp_ptr[7] += uik[12]*u[4]+ uik[13]*u[5]+ uik[14]*u[6]+ uik[15]*u[7];

          rtmp_ptr[8] += uik[0]*u[8] + uik[1]*u[9] + uik[2]*u[10] + uik[3]*u[11];
          rtmp_ptr[9] += uik[4]*u[8] + uik[5]*u[9] + uik[6]*u[10] + uik[7]*u[11];
          rtmp_ptr[10]+= uik[8]*u[8] + uik[9]*u[9] + uik[10]*u[10]+ uik[11]*u[11];
          rtmp_ptr[11]+= uik[12]*u[8]+ uik[13]*u[9]+ uik[14]*u[10]+ uik[15]*u[11];

          rtmp_ptr[12]+= uik[0]*u[12] + uik[1]*u[13] + uik[2]*u[14] + uik[3]*u[15];
          rtmp_ptr[13]+= uik[4]*u[12] + uik[5]*u[13] + uik[6]*u[14] + uik[7]*u[15];
          rtmp_ptr[14]+= uik[8]*u[12] + uik[9]*u[13] + uik[10]*u[14]+ uik[11]*u[15];
          rtmp_ptr[15]+= uik[12]*u[12]+ uik[13]*u[13]+ uik[14]*u[14]+ uik[15]*u[15];
        }
        ierr = PetscLogFlops(2.0*64.0*(jmax-jmin));CHKERRQ(ierr);

        /* ... add i to row list for next nonzero entry */
        il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
        j     = bj[jmin];
        jl[i] = jl[j]; jl[j] = i; /* update jl */
      }
      i = nexti;
    }

    /* save nonzero entries in k-th row of U ... */

    /* invert diagonal block */
    diag = ba+k*16;
    ierr = PetscMemcpy(diag,dk,16*sizeof(MatScalar));CHKERRQ(ierr);
    if (pivotinblocks) {
      ierr = PetscKernel_A_gets_inverse_A_4(diag,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
      if (zeropivotdetected) C->errortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
    } else {
      ierr = PetscKernel_A_gets_inverse_A_4_nopivot(diag);CHKERRQ(ierr);
    }

    jmin = bi[k]; jmax = bi[k+1];
    if (jmin < jmax) {
      for (j=jmin; j<jmax; j++) {
        vj       = bj[j];      /* block col. index of U */
        u        = ba + j*16;
        rtmp_ptr = rtmp + vj*16;
        for (k1=0; k1<16; k1++) {
          *u++        = *rtmp_ptr;
          *rtmp_ptr++ = 0.0;
        }
      }

      /* ... add k to row list for first nonzero entry in k-th row */
      il[k] = jmin;
      i     = bj[jmin];
      jl[k] = jl[i]; jl[i] = k;
    }
  }

  ierr = PetscFree(rtmp);CHKERRQ(ierr);
  ierr = PetscFree2(il,jl);CHKERRQ(ierr);
  ierr = PetscFree2(dk,uik);CHKERRQ(ierr);

  C->ops->solve          = MatSolve_SeqSBAIJ_4_NaturalOrdering_inplace;
  C->ops->solvetranspose = MatSolve_SeqSBAIJ_4_NaturalOrdering_inplace;
  C->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_4_NaturalOrdering_inplace;
  C->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_4_NaturalOrdering_inplace;

  C->assembled    = PETSC_TRUE;
  C->preallocated = PETSC_TRUE;

  ierr = PetscLogFlops(1.3333*64*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
  PetscFunctionReturn(0);
}
Example #3
0
PetscErrorCode MatLUFactorNumeric_SeqBAIJ_3_NaturalOrdering_inplace(Mat C,Mat A,const MatFactorInfo *info)
{
  Mat_SeqBAIJ    *a = (Mat_SeqBAIJ*)A->data,*b = (Mat_SeqBAIJ*)C->data;
  PetscErrorCode ierr;
  PetscInt       i,j,n = a->mbs,*bi = b->i,*bj = b->j;
  PetscInt       *ajtmpold,*ajtmp,nz,row;
  PetscInt       *diag_offset = b->diag,*ai=a->i,*aj=a->j,*pj;
  MatScalar      *pv,*v,*rtmp,*pc,*w,*x;
  MatScalar      p1,p2,p3,p4,m1,m2,m3,m4,m5,m6,m7,m8,m9,x1,x2,x3,x4;
  MatScalar      p5,p6,p7,p8,p9,x5,x6,x7,x8,x9;
  MatScalar      *ba   = b->a,*aa = a->a;
  PetscReal      shift = info->shiftamount;
  PetscBool      allowzeropivot,zeropivotdetected;

  PetscFunctionBegin;
  ierr = PetscMalloc1(9*(n+1),&rtmp);CHKERRQ(ierr);
  allowzeropivot = PetscNot(A->erroriffailure);

  for (i=0; i<n; i++) {
    nz    = bi[i+1] - bi[i];
    ajtmp = bj + bi[i];
    for  (j=0; j<nz; j++) {
      x    = rtmp+9*ajtmp[j];
      x[0] = x[1]  = x[2]  = x[3]  = x[4]  = x[5]  = x[6] = x[7] = x[8] = 0.0;
    }
    /* load in initial (unfactored row) */
    nz       = ai[i+1] - ai[i];
    ajtmpold = aj + ai[i];
    v        = aa + 9*ai[i];
    for (j=0; j<nz; j++) {
      x    = rtmp+9*ajtmpold[j];
      x[0] = v[0];  x[1]  = v[1];  x[2]  = v[2];  x[3]  = v[3];
      x[4] = v[4];  x[5]  = v[5];  x[6]  = v[6];  x[7]  = v[7];  x[8]  = v[8];
      v   += 9;
    }
    row = *ajtmp++;
    while (row < i) {
      pc = rtmp + 9*row;
      p1 = pc[0];  p2  = pc[1];  p3  = pc[2];  p4  = pc[3];
      p5 = pc[4];  p6  = pc[5];  p7  = pc[6];  p8  = pc[7];  p9  = pc[8];
      if (p1 != 0.0 || p2 != 0.0 || p3 != 0.0 || p4 != 0.0 || p5 != 0.0 ||
          p6 != 0.0 || p7 != 0.0 || p8 != 0.0 || p9 != 0.0) {
        pv    = ba + 9*diag_offset[row];
        pj    = bj + diag_offset[row] + 1;
        x1    = pv[0];  x2  = pv[1];  x3  = pv[2];  x4  = pv[3];
        x5    = pv[4];  x6  = pv[5];  x7  = pv[6];  x8  = pv[7];  x9  = pv[8];
        pc[0] = m1 = p1*x1 + p4*x2 + p7*x3;
        pc[1] = m2 = p2*x1 + p5*x2 + p8*x3;
        pc[2] = m3 = p3*x1 + p6*x2 + p9*x3;

        pc[3] = m4 = p1*x4 + p4*x5 + p7*x6;
        pc[4] = m5 = p2*x4 + p5*x5 + p8*x6;
        pc[5] = m6 = p3*x4 + p6*x5 + p9*x6;

        pc[6] = m7 = p1*x7 + p4*x8 + p7*x9;
        pc[7] = m8 = p2*x7 + p5*x8 + p8*x9;
        pc[8] = m9 = p3*x7 + p6*x8 + p9*x9;

        nz  = bi[row+1] - diag_offset[row] - 1;
        pv += 9;
        for (j=0; j<nz; j++) {
          x1    = pv[0];  x2  = pv[1];   x3 = pv[2];  x4  = pv[3];
          x5    = pv[4];  x6  = pv[5];   x7 = pv[6];  x8  = pv[7]; x9 = pv[8];
          x     = rtmp + 9*pj[j];
          x[0] -= m1*x1 + m4*x2 + m7*x3;
          x[1] -= m2*x1 + m5*x2 + m8*x3;
          x[2] -= m3*x1 + m6*x2 + m9*x3;

          x[3] -= m1*x4 + m4*x5 + m7*x6;
          x[4] -= m2*x4 + m5*x5 + m8*x6;
          x[5] -= m3*x4 + m6*x5 + m9*x6;

          x[6] -= m1*x7 + m4*x8 + m7*x9;
          x[7] -= m2*x7 + m5*x8 + m8*x9;
          x[8] -= m3*x7 + m6*x8 + m9*x9;
          pv   += 9;
        }
        ierr = PetscLogFlops(54.0*nz+36.0);CHKERRQ(ierr);
      }
      row = *ajtmp++;
    }
    /* finished row so stick it into b->a */
    pv = ba + 9*bi[i];
    pj = bj + bi[i];
    nz = bi[i+1] - bi[i];
    for (j=0; j<nz; j++) {
      x     = rtmp+9*pj[j];
      pv[0] = x[0];  pv[1]  = x[1];  pv[2]  = x[2];  pv[3]  = x[3];
      pv[4] = x[4];  pv[5]  = x[5];  pv[6]  = x[6];  pv[7]  = x[7]; pv[8] = x[8];
      pv   += 9;
    }
    /* invert diagonal block */
    w    = ba + 9*diag_offset[i];
    ierr = PetscKernel_A_gets_inverse_A_3(w,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
    if (zeropivotdetected) C->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;
  }

  ierr = PetscFree(rtmp);CHKERRQ(ierr);

  C->ops->solve          = MatSolve_SeqBAIJ_3_NaturalOrdering_inplace;
  C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_3_NaturalOrdering_inplace;
  C->assembled           = PETSC_TRUE;

  ierr = PetscLogFlops(1.333333333333*3*3*3*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
  PetscFunctionReturn(0);
}
Example #4
0
/*
  MatLUFactorNumeric_SeqBAIJ_3_NaturalOrdering -
    copied from MatLUFactorNumeric_SeqBAIJ_2_NaturalOrdering_inplace()
*/
PetscErrorCode MatLUFactorNumeric_SeqBAIJ_3_NaturalOrdering(Mat B,Mat A,const MatFactorInfo *info)
{
  Mat            C =B;
  Mat_SeqBAIJ    *a=(Mat_SeqBAIJ*)A->data,*b=(Mat_SeqBAIJ*)C->data;
  PetscErrorCode ierr;
  PetscInt       i,j,k,nz,nzL,row;
  const PetscInt n=a->mbs,*ai=a->i,*aj=a->j,*bi=b->i,*bj=b->j;
  const PetscInt *ajtmp,*bjtmp,*bdiag=b->diag,*pj,bs2=a->bs2;
  MatScalar      *rtmp,*pc,*mwork,*v,*pv,*aa=a->a;
  PetscInt       flg;
  PetscReal      shift = info->shiftamount;
  PetscBool      allowzeropivot,zeropivotdetected;

  PetscFunctionBegin;
  allowzeropivot = PetscNot(A->erroriffailure);

  /* generate work space needed by the factorization */
  ierr = PetscMalloc2(bs2*n,&rtmp,bs2,&mwork);CHKERRQ(ierr);
  ierr = PetscMemzero(rtmp,bs2*n*sizeof(MatScalar));CHKERRQ(ierr);

  for (i=0; i<n; i++) {
    /* zero rtmp */
    /* L part */
    nz    = bi[i+1] - bi[i];
    bjtmp = bj + bi[i];
    for  (j=0; j<nz; j++) {
      ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
    }

    /* U part */
    nz    = bdiag[i] - bdiag[i+1];
    bjtmp = bj + bdiag[i+1] + 1;
    for  (j=0; j<nz; j++) {
      ierr = PetscMemzero(rtmp+bs2*bjtmp[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
    }

    /* load in initial (unfactored row) */
    nz    = ai[i+1] - ai[i];
    ajtmp = aj + ai[i];
    v     = aa + bs2*ai[i];
    for (j=0; j<nz; j++) {
      ierr = PetscMemcpy(rtmp+bs2*ajtmp[j],v+bs2*j,bs2*sizeof(MatScalar));CHKERRQ(ierr);
    }

    /* elimination */
    bjtmp = bj + bi[i];
    nzL   = bi[i+1] - bi[i];
    for (k=0; k<nzL; k++) {
      row = bjtmp[k];
      pc  = rtmp + bs2*row;
      for (flg=0,j=0; j<bs2; j++) {
        if (pc[j]!=0.0) {
          flg = 1;
          break;
        }
      }
      if (flg) {
        pv = b->a + bs2*bdiag[row];
        /* PetscKernel_A_gets_A_times_B(bs,pc,pv,mwork); *pc = *pc * (*pv); */
        ierr = PetscKernel_A_gets_A_times_B_3(pc,pv,mwork);CHKERRQ(ierr);

        pj = b->j + bdiag[row+1]+1; /* beginning of U(row,:) */
        pv = b->a + bs2*(bdiag[row+1]+1);
        nz = bdiag[row] - bdiag[row+1] - 1; /* num of entries in U(row,:) excluding diag */
        for (j=0; j<nz; j++) {
          /* PetscKernel_A_gets_A_minus_B_times_C(bs,rtmp+bs2*pj[j],pc,pv+bs2*j); */
          /* rtmp+bs2*pj[j] = rtmp+bs2*pj[j] - (*pc)*(pv+bs2*j) */
          v    = rtmp + bs2*pj[j];
          ierr = PetscKernel_A_gets_A_minus_B_times_C_3(v,pc,pv);CHKERRQ(ierr);
          pv  += bs2;
        }
        ierr = PetscLogFlops(54*nz+45);CHKERRQ(ierr); /* flops = 2*bs^3*nz + 2*bs^3 - bs2) */
      }
    }

    /* finished row so stick it into b->a */
    /* L part */
    pv = b->a + bs2*bi[i];
    pj = b->j + bi[i];
    nz = bi[i+1] - bi[i];
    for (j=0; j<nz; j++) {
      ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
    }

    /* Mark diagonal and invert diagonal for simplier triangular solves */
    pv   = b->a + bs2*bdiag[i];
    pj   = b->j + bdiag[i];
    ierr = PetscMemcpy(pv,rtmp+bs2*pj[0],bs2*sizeof(MatScalar));CHKERRQ(ierr);
    ierr = PetscKernel_A_gets_inverse_A_3(pv,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
    if (zeropivotdetected) B->factorerrortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;

    /* U part */
    pv = b->a + bs2*(bdiag[i+1]+1);
    pj = b->j + bdiag[i+1]+1;
    nz = bdiag[i] - bdiag[i+1] - 1;
    for (j=0; j<nz; j++) {
      ierr = PetscMemcpy(pv+bs2*j,rtmp+bs2*pj[j],bs2*sizeof(MatScalar));CHKERRQ(ierr);
    }
  }
  ierr = PetscFree2(rtmp,mwork);CHKERRQ(ierr);

  C->ops->solve          = MatSolve_SeqBAIJ_3_NaturalOrdering;
  C->ops->forwardsolve   = MatForwardSolve_SeqBAIJ_3_NaturalOrdering;
  C->ops->backwardsolve  = MatBackwardSolve_SeqBAIJ_3_NaturalOrdering;
  C->ops->solvetranspose = MatSolveTranspose_SeqBAIJ_3_NaturalOrdering;
  C->assembled           = PETSC_TRUE;

  ierr = PetscLogFlops(1.333333333333*3*3*3*n);CHKERRQ(ierr); /* from inverting diagonal blocks */
  PetscFunctionReturn(0);
}
Example #5
0
PetscErrorCode MatCholeskyFactorNumeric_SeqSBAIJ_6_NaturalOrdering(Mat C,Mat A,const MatFactorInfo *info)
{
  Mat_SeqSBAIJ   *a = (Mat_SeqSBAIJ*)A->data,*b = (Mat_SeqSBAIJ*)C->data;
  PetscErrorCode ierr;
  PetscInt       i,j,mbs=a->mbs,*bi=b->i,*bj=b->j;
  PetscInt       *ai,*aj,k,k1,jmin,jmax,*jl,*il,vj,nexti,ili;
  MatScalar      *ba = b->a,*aa,*ap,*dk,*uik;
  MatScalar      *u,*d,*w,*wp,u0,u1,u2,u3,u4,u5,u6,u7,u8,u9,u10,u11,u12;
  MatScalar      u13,u14,u15,u16,u17,u18,u19,u20,u21,u22,u23,u24,u25,u26,u27;
  MatScalar      u28,u29,u30,u31,u32,u33,u34,u35;
  MatScalar      d0,d1,d2,d3,d4,d5,d6,d7,d8,d9,d10,d11,d12;
  MatScalar      d13,d14,d15,d16,d17,d18,d19,d20,d21,d22,d23,d24,d25,d26,d27;
  MatScalar      d28,d29,d30,d31,d32,d33,d34,d35;
  MatScalar      m0,m1,m2,m3,m4,m5,m6,m7,m8,m9,m10,m11,m12;
  MatScalar      m13,m14,m15,m16,m17,m18,m19,m20,m21,m22,m23,m24,m25,m26,m27;
  MatScalar      m28,m29,m30,m31,m32,m33,m34,m35;
  PetscReal      shift = info->shiftamount;
  PetscBool      allowzeropivot,zeropivotdetected;

  PetscFunctionBegin;
  /* initialization */
  allowzeropivot = PetscNot(A->erroriffailure);
  ierr = PetscCalloc1(36*mbs,&w);CHKERRQ(ierr);
  ierr = PetscMalloc2(mbs,&il,mbs,&jl);CHKERRQ(ierr);
  for (i=0; i<mbs; i++) {
    jl[i] = mbs; il[0] = 0;
  }
  ierr = PetscMalloc2(36,&dk,36,&uik);CHKERRQ(ierr);
  ai   = a->i; aj = a->j; aa = a->a;

  /* for each row k */
  for (k = 0; k<mbs; k++) {

    /*initialize k-th row with elements nonzero in row k of A */
    jmin = ai[k]; jmax = ai[k+1];
    if (jmin < jmax) {
      ap = aa + jmin*36;
      for (j = jmin; j < jmax; j++) {
        vj = aj[j];         /* block col. index */
        wp = w + vj*36;
        for (i=0; i<36; i++) *wp++ = *ap++;
      }
    }

    /* modify k-th row by adding in those rows i with U(i,k) != 0 */
    ierr = PetscMemcpy(dk,w+k*36,36*sizeof(MatScalar));CHKERRQ(ierr);
    i    = jl[k]; /* first row to be added to k_th row  */

    while (i < mbs) {
      nexti = jl[i]; /* next row to be added to k_th row */

      /* compute multiplier */
      ili = il[i];  /* index of first nonzero element in U(i,k:bms-1) */

      /* uik = -inv(Di)*U_bar(i,k) */
      d = ba + i*36;
      u = ba + ili*36;

      u0  = u[0]; u1 = u[1]; u2 = u[2]; u3 = u[3]; u4 = u[4]; u5 = u[5]; u6 = u[6];
      u7  = u[7]; u8 = u[8]; u9 = u[9]; u10 = u[10]; u11 = u[11]; u12 = u[12]; u13 = u[13];
      u14 = u[14]; u15 = u[15]; u16 = u[16]; u17 = u[17]; u18 = u[18]; u19 = u[19]; u20 = u[20];
      u21 = u[21]; u22 = u[22]; u23 = u[23]; u24 = u[24]; u25 = u[25]; u26 = u[26]; u27 = u[27];
      u28 = u[28]; u29 = u[29]; u30 = u[30]; u31 = u[31]; u32 = u[32]; u33 = u[33]; u34 = u[34];
      u35 = u[35];

      d0  = d[0];  d1  = d[1];  d2  = d[2];  d3  = d[3];
      d4  = d[4];  d5  = d[5];  d6  = d[6];  d7  = d[7];
      d8  = d[8];  d9 = d[9];  d10 = d[10]; d11 = d[11];
      d12 = d[12]; d13 = d[13]; d14 = d[14]; d15 = d[15];
      d16 = d[16]; d17 = d[17]; d18 = d[18]; d19 = d[19];
      d20 = d[20]; d21 = d[21]; d22 = d[22]; d23 = d[23];
      d24 = d[24]; d25 = d[25]; d26 = d[26]; d27 = d[27];
      d28 = d[28]; d29 = d[29]; d30 = d[30]; d31 = d[31];
      d32 = d[32]; d33 = d[33]; d34 = d[34]; d35 = d[35];

      m0 = uik[0] = -(d0*u0 + d6*u1 + d12*u2 + d18*u3 + d24*u4 + d30*u5);
      m1 = uik[1] = -(d1*u0 + d7*u1 + d13*u2 + d19*u3 + d25*u4 + d31*u5);
      m2 = uik[2] = -(d2*u0 + d8*u1 + d14*u2 + d20*u3 + d26*u4 + d32*u5);
      m3 = uik[3] = -(d3*u0 + d9*u1 + d15*u2 + d21*u3 + d27*u4 + d33*u5);
      m4 = uik[4] = -(d4*u0+ d10*u1 + d16*u2 + d22*u3 + d28*u4 + d34*u5);
      m5 = uik[5] = -(d5*u0+ d11*u1 + d17*u2 + d23*u3 + d29*u4 + d35*u5);

      m6  = uik[6] = -(d0*u6 + d6*u7 + d12*u8 + d18*u9 + d24*u10 + d30*u11);
      m7  = uik[7] = -(d1*u6 + d7*u7 + d13*u8 + d19*u9 + d25*u10 + d31*u11);
      m8  = uik[8] = -(d2*u6 + d8*u7 + d14*u8 + d20*u9 + d26*u10 + d32*u11);
      m9  = uik[9] = -(d3*u6 + d9*u7 + d15*u8 + d21*u9 + d27*u10 + d33*u11);
      m10 = uik[10]= -(d4*u6+ d10*u7 + d16*u8 + d22*u9 + d28*u10 + d34*u11);
      m11 = uik[11]= -(d5*u6+ d11*u7 + d17*u8 + d23*u9 + d29*u10 + d35*u11);

      m12 = uik[12] = -(d0*u12 + d6*u13 + d12*u14 + d18*u15 + d24*u16 + d30*u17);
      m13 = uik[13] = -(d1*u12 + d7*u13 + d13*u14 + d19*u15 + d25*u16 + d31*u17);
      m14 = uik[14] = -(d2*u12 + d8*u13 + d14*u14 + d20*u15 + d26*u16 + d32*u17);
      m15 = uik[15] = -(d3*u12 + d9*u13 + d15*u14 + d21*u15 + d27*u16 + d33*u17);
      m16 = uik[16] = -(d4*u12+ d10*u13 + d16*u14 + d22*u15 + d28*u16 + d34*u17);
      m17 = uik[17] = -(d5*u12+ d11*u13 + d17*u14 + d23*u15 + d29*u16 + d35*u17);

      m18 = uik[18] = -(d0*u18 + d6*u19 + d12*u20 + d18*u21 + d24*u22 + d30*u23);
      m19 = uik[19] = -(d1*u18 + d7*u19 + d13*u20 + d19*u21 + d25*u22 + d31*u23);
      m20 = uik[20] = -(d2*u18 + d8*u19 + d14*u20 + d20*u21 + d26*u22 + d32*u23);
      m21 = uik[21] = -(d3*u18 + d9*u19 + d15*u20 + d21*u21 + d27*u22 + d33*u23);
      m22 = uik[22] = -(d4*u18+ d10*u19 + d16*u20 + d22*u21 + d28*u22 + d34*u23);
      m23 = uik[23] = -(d5*u18+ d11*u19 + d17*u20 + d23*u21 + d29*u22 + d35*u23);

      m24 = uik[24] = -(d0*u24 + d6*u25 + d12*u26 + d18*u27 + d24*u28 + d30*u29);
      m25 = uik[25] = -(d1*u24 + d7*u25 + d13*u26 + d19*u27 + d25*u28 + d31*u29);
      m26 = uik[26] = -(d2*u24 + d8*u25 + d14*u26 + d20*u27 + d26*u28 + d32*u29);
      m27 = uik[27] = -(d3*u24 + d9*u25 + d15*u26 + d21*u27 + d27*u28 + d33*u29);
      m28 = uik[28] = -(d4*u24+ d10*u25 + d16*u26 + d22*u27 + d28*u28 + d34*u29);
      m29 = uik[29] = -(d5*u24+ d11*u25 + d17*u26 + d23*u27 + d29*u28 + d35*u29);

      m30 = uik[30] = -(d0*u30 + d6*u31 + d12*u32 + d18*u33 + d24*u34 + d30*u35);
      m31 = uik[31] = -(d1*u30 + d7*u31 + d13*u32 + d19*u33 + d25*u34 + d31*u35);
      m32 = uik[32] = -(d2*u30 + d8*u31 + d14*u32 + d20*u33 + d26*u34 + d32*u35);
      m33 = uik[33] = -(d3*u30 + d9*u31 + d15*u32 + d21*u33 + d27*u34 + d33*u35);
      m34 = uik[34] = -(d4*u30+ d10*u31 + d16*u32 + d22*u33 + d28*u34 + d34*u35);
      m35 = uik[35] = -(d5*u30+ d11*u31 + d17*u32 + d23*u33 + d29*u34 + d35*u35);

      /* update D(k) += -U(i,k)^T * U_bar(i,k) */
      dk[0] +=  m0*u0 + m1*u1 + m2*u2 + m3*u3 + m4*u4 + m5*u5;
      dk[1] +=  m6*u0 + m7*u1 + m8*u2 + m9*u3+ m10*u4+ m11*u5;
      dk[2] += m12*u0+ m13*u1+ m14*u2+ m15*u3+ m16*u4+ m17*u5;
      dk[3] += m18*u0+ m19*u1+ m20*u2+ m21*u3+ m22*u4+ m23*u5;
      dk[4] += m24*u0+ m25*u1+ m26*u2+ m27*u3+ m28*u4+ m29*u5;
      dk[5] += m30*u0+ m31*u1+ m32*u2+ m33*u3+ m34*u4+ m35*u5;

      dk[6] +=  m0*u6 + m1*u7 + m2*u8 + m3*u9 + m4*u10 + m5*u11;
      dk[7] +=  m6*u6 + m7*u7 + m8*u8 + m9*u9+ m10*u10+ m11*u11;
      dk[8] += m12*u6+ m13*u7+ m14*u8+ m15*u9+ m16*u10+ m17*u11;
      dk[9] += m18*u6+ m19*u7+ m20*u8+ m21*u9+ m22*u10+ m23*u11;
      dk[10]+= m24*u6+ m25*u7+ m26*u8+ m27*u9+ m28*u10+ m29*u11;
      dk[11]+= m30*u6+ m31*u7+ m32*u8+ m33*u9+ m34*u10+ m35*u11;

      dk[12]+=  m0*u12 + m1*u13 + m2*u14 + m3*u15 + m4*u16 + m5*u17;
      dk[13]+=  m6*u12 + m7*u13 + m8*u14 + m9*u15+ m10*u16+ m11*u17;
      dk[14]+= m12*u12+ m13*u13+ m14*u14+ m15*u15+ m16*u16+ m17*u17;
      dk[15]+= m18*u12+ m19*u13+ m20*u14+ m21*u15+ m22*u16+ m23*u17;
      dk[16]+= m24*u12+ m25*u13+ m26*u14+ m27*u15+ m28*u16+ m29*u17;
      dk[17]+= m30*u12+ m31*u13+ m32*u14+ m33*u15+ m34*u16+ m35*u17;

      dk[18]+=  m0*u18 + m1*u19 + m2*u20 + m3*u21 + m4*u22 + m5*u23;
      dk[19]+=  m6*u18 + m7*u19 + m8*u20 + m9*u21+ m10*u22+ m11*u23;
      dk[20]+= m12*u18+ m13*u19+ m14*u20+ m15*u21+ m16*u22+ m17*u23;
      dk[21]+= m18*u18+ m19*u19+ m20*u20+ m21*u21+ m22*u22+ m23*u23;
      dk[22]+= m24*u18+ m25*u19+ m26*u20+ m27*u21+ m28*u22+ m29*u23;
      dk[23]+= m30*u18+ m31*u19+ m32*u20+ m33*u21+ m34*u22+ m35*u23;

      dk[24]+=  m0*u24 + m1*u25 + m2*u26 + m3*u27 + m4*u28 + m5*u29;
      dk[25]+=  m6*u24 + m7*u25 + m8*u26 + m9*u27+ m10*u28+ m11*u29;
      dk[26]+= m12*u24+ m13*u25+ m14*u26+ m15*u27+ m16*u28+ m17*u29;
      dk[27]+= m18*u24+ m19*u25+ m20*u26+ m21*u27+ m22*u28+ m23*u29;
      dk[28]+= m24*u24+ m25*u25+ m26*u26+ m27*u27+ m28*u28+ m29*u29;
      dk[29]+= m30*u24+ m31*u25+ m32*u26+ m33*u27+ m34*u28+ m35*u29;

      dk[30]+=  m0*u30 + m1*u31 + m2*u32 + m3*u33 + m4*u34 + m5*u35;
      dk[31]+=  m6*u30 + m7*u31 + m8*u32 + m9*u33+ m10*u34+ m11*u35;
      dk[32]+= m12*u30+ m13*u31+ m14*u32+ m15*u33+ m16*u34+ m17*u35;
      dk[33]+= m18*u30+ m19*u31+ m20*u32+ m21*u33+ m22*u34+ m23*u35;
      dk[34]+= m24*u30+ m25*u31+ m26*u32+ m27*u33+ m28*u34+ m29*u35;
      dk[35]+= m30*u30+ m31*u31+ m32*u32+ m33*u33+ m34*u34+ m35*u35;

      ierr = PetscLogFlops(216.0*4.0);CHKERRQ(ierr);

      /* update -U(i,k) */
      ierr = PetscMemcpy(ba+ili*36,uik,36*sizeof(MatScalar));CHKERRQ(ierr);

      /* add multiple of row i to k-th row ... */
      jmin = ili + 1; jmax = bi[i+1];
      if (jmin < jmax) {
        for (j=jmin; j<jmax; j++) {
          /* w += -U(i,k)^T * U_bar(i,j) */
          wp = w + bj[j]*36;
          u  = ba + j*36;

          u0  = u[0];  u1  = u[1];  u2  = u[2];  u3  = u[3];  u4  = u[4];  u5  = u[5];  u6  = u[6];
          u7  = u[7];  u8  = u[8];  u9  = u[9];  u10 = u[10]; u11 = u[11]; u12 = u[12]; u13 = u[13];
          u14 = u[14]; u15 = u[15]; u16 = u[16]; u17 = u[17]; u18 = u[18]; u19 = u[19]; u20 = u[20];
          u21 = u[21]; u22 = u[22]; u23 = u[23]; u24 = u[24]; u25 = u[25]; u26 = u[26]; u27 = u[27];
          u28 = u[28]; u29 = u[29]; u30 = u[30]; u31 = u[31]; u32 = u[32]; u33 = u[33]; u34 = u[34];
          u35 = u[35];

          wp[0] +=  m0*u0 + m1*u1 + m2*u2 + m3*u3 + m4*u4 + m5*u5;
          wp[1] +=  m6*u0 + m7*u1 + m8*u2 + m9*u3+ m10*u4+ m11*u5;
          wp[2] += m12*u0+ m13*u1+ m14*u2+ m15*u3+ m16*u4+ m17*u5;
          wp[3] += m18*u0+ m19*u1+ m20*u2+ m21*u3+ m22*u4+ m23*u5;
          wp[4] += m24*u0+ m25*u1+ m26*u2+ m27*u3+ m28*u4+ m29*u5;
          wp[5] += m30*u0+ m31*u1+ m32*u2+ m33*u3+ m34*u4+ m35*u5;

          wp[6] +=  m0*u6 + m1*u7 + m2*u8 + m3*u9 + m4*u10 + m5*u11;
          wp[7] +=  m6*u6 + m7*u7 + m8*u8 + m9*u9+ m10*u10+ m11*u11;
          wp[8] += m12*u6+ m13*u7+ m14*u8+ m15*u9+ m16*u10+ m17*u11;
          wp[9] += m18*u6+ m19*u7+ m20*u8+ m21*u9+ m22*u10+ m23*u11;
          wp[10]+= m24*u6+ m25*u7+ m26*u8+ m27*u9+ m28*u10+ m29*u11;
          wp[11]+= m30*u6+ m31*u7+ m32*u8+ m33*u9+ m34*u10+ m35*u11;

          wp[12]+=  m0*u12 + m1*u13 + m2*u14 + m3*u15 + m4*u16 + m5*u17;
          wp[13]+=  m6*u12 + m7*u13 + m8*u14 + m9*u15+ m10*u16+ m11*u17;
          wp[14]+= m12*u12+ m13*u13+ m14*u14+ m15*u15+ m16*u16+ m17*u17;
          wp[15]+= m18*u12+ m19*u13+ m20*u14+ m21*u15+ m22*u16+ m23*u17;
          wp[16]+= m24*u12+ m25*u13+ m26*u14+ m27*u15+ m28*u16+ m29*u17;
          wp[17]+= m30*u12+ m31*u13+ m32*u14+ m33*u15+ m34*u16+ m35*u17;

          wp[18]+=  m0*u18 + m1*u19 + m2*u20 + m3*u21 + m4*u22 + m5*u23;
          wp[19]+=  m6*u18 + m7*u19 + m8*u20 + m9*u21+ m10*u22+ m11*u23;
          wp[20]+= m12*u18+ m13*u19+ m14*u20+ m15*u21+ m16*u22+ m17*u23;
          wp[21]+= m18*u18+ m19*u19+ m20*u20+ m21*u21+ m22*u22+ m23*u23;
          wp[22]+= m24*u18+ m25*u19+ m26*u20+ m27*u21+ m28*u22+ m29*u23;
          wp[23]+= m30*u18+ m31*u19+ m32*u20+ m33*u21+ m34*u22+ m35*u23;

          wp[24]+=  m0*u24 + m1*u25 + m2*u26 + m3*u27 + m4*u28 + m5*u29;
          wp[25]+=  m6*u24 + m7*u25 + m8*u26 + m9*u27+ m10*u28+ m11*u29;
          wp[26]+= m12*u24+ m13*u25+ m14*u26+ m15*u27+ m16*u28+ m17*u29;
          wp[27]+= m18*u24+ m19*u25+ m20*u26+ m21*u27+ m22*u28+ m23*u29;
          wp[28]+= m24*u24+ m25*u25+ m26*u26+ m27*u27+ m28*u28+ m29*u29;
          wp[29]+= m30*u24+ m31*u25+ m32*u26+ m33*u27+ m34*u28+ m35*u29;

          wp[30]+=  m0*u30 + m1*u31 + m2*u32 + m3*u33 + m4*u34 + m5*u35;
          wp[31]+=  m6*u30 + m7*u31 + m8*u32 + m9*u33+ m10*u34+ m11*u35;
          wp[32]+= m12*u30+ m13*u31+ m14*u32+ m15*u33+ m16*u34+ m17*u35;
          wp[33]+= m18*u30+ m19*u31+ m20*u32+ m21*u33+ m22*u34+ m23*u35;
          wp[34]+= m24*u30+ m25*u31+ m26*u32+ m27*u33+ m28*u34+ m29*u35;
          wp[35]+= m30*u30+ m31*u31+ m32*u32+ m33*u33+ m34*u34+ m35*u35;
        }
        ierr = PetscLogFlops(2.0*216.0*(jmax-jmin));CHKERRQ(ierr);

        /* ... add i to row list for next nonzero entry */
        il[i] = jmin;             /* update il(i) in column k+1, ... mbs-1 */
        j     = bj[jmin];
        jl[i] = jl[j]; jl[j] = i; /* update jl */
      }
      i = nexti;
    }

    /* save nonzero entries in k-th row of U ... */

    /* invert diagonal block */
    d    = ba+k*36;
    ierr = PetscMemcpy(d,dk,36*sizeof(MatScalar));CHKERRQ(ierr);
    ierr = PetscKernel_A_gets_inverse_A_6(d,shift,allowzeropivot,&zeropivotdetected);CHKERRQ(ierr);
    if (zeropivotdetected) C->errortype = MAT_FACTOR_NUMERIC_ZEROPIVOT;

    jmin = bi[k]; jmax = bi[k+1];
    if (jmin < jmax) {
      for (j=jmin; j<jmax; j++) {
        vj = bj[j];            /* block col. index of U */
        u  = ba + j*36;
        wp = w + vj*36;
        for (k1=0; k1<36; k1++) {
          *u++  = *wp;
          *wp++ = 0.0;
        }
      }

      /* ... add k to row list for first nonzero entry in k-th row */
      il[k] = jmin;
      i     = bj[jmin];
      jl[k] = jl[i]; jl[i] = k;
    }
  }

  ierr = PetscFree(w);CHKERRQ(ierr);
  ierr = PetscFree2(il,jl);CHKERRQ(ierr);
  ierr = PetscFree2(dk,uik);CHKERRQ(ierr);

  C->ops->solve          = MatSolve_SeqSBAIJ_6_NaturalOrdering_inplace;
  C->ops->solvetranspose = MatSolve_SeqSBAIJ_6_NaturalOrdering_inplace;
  C->ops->forwardsolve   = MatForwardSolve_SeqSBAIJ_6_NaturalOrdering_inplace;
  C->ops->backwardsolve  = MatBackwardSolve_SeqSBAIJ_6_NaturalOrdering_inplace;
  C->assembled           = PETSC_TRUE;
  C->preallocated        = PETSC_TRUE;

  ierr = PetscLogFlops(1.3333*216*b->mbs);CHKERRQ(ierr); /* from inverting diagonal blocks */
  PetscFunctionReturn(0);
}