DistMultiVec<T>
DistMultiVec<T>::operator()( const vector<Int>& I, const vector<Int>& J ) const
{
DEBUG_ONLY(CSE cse("DistMultiVec::operator()"))
DistMultiVec<T> ASub(this->Comm());
GetSubmatrix( *this, I, J, ASub );
return ASub;
}
void Tikhonov
( Orientation orientation,
const DistSparseMatrix<F>& A,
const DistMultiVec<F>& B,
const DistSparseMatrix<F>& G,
DistMultiVec<F>& X,
const LeastSquaresCtrl<Base<F>>& ctrl )
{
DEBUG_CSE
mpi::Comm comm = A.Comm();
// Explicitly form W := op(A)
// ==========================
DistSparseMatrix<F> W(comm);
if( orientation == NORMAL )
W = A;
else if( orientation == TRANSPOSE )
Transpose( A, W );
else
Adjoint( A, W );
const Int m = W.Height();
const Int n = W.Width();
const Int numRHS = B.Width();
// Embed into a higher-dimensional problem via appending regularization
// ====================================================================
DistSparseMatrix<F> WEmb(comm);
if( m >= n )
VCat( W, G, WEmb );
else
HCat( W, G, WEmb );
DistMultiVec<F> BEmb(comm);
Zeros( BEmb, WEmb.Height(), numRHS );
if( m >= n )
{
// BEmb := [B; 0]
// --------------
const Int mLocB = B.LocalHeight();
BEmb.Reserve( mLocB*numRHS );
for( Int iLoc=0; iLoc<mLocB; ++iLoc )
{
const Int i = B.GlobalRow(iLoc);
for( Int j=0; j<numRHS; ++j )
BEmb.QueueUpdate( i, j, B.GetLocal(iLoc,j) );
}
BEmb.ProcessQueues();
}
else
BEmb = B;
// Solve the higher-dimensional problem
// ====================================
DistMultiVec<F> XEmb(comm);
LeastSquares( NORMAL, WEmb, BEmb, XEmb, ctrl );
// Extract the solution
// ====================
if( m >= n )
X = XEmb;
else
GetSubmatrix( XEmb, IR(0,n), IR(0,numRHS), X );
}