void PartialColScatter
( T alpha,
const ElementalMatrix<T>& A,
ElementalMatrix<T>& B )
{
DEBUG_ONLY(CSE cse("axpy_contract::PartialColScatter"))
AssertSameGrids( A, B );
if( A.Height() != B.Height() || A.Width() != B.Width() )
LogicError("A and B must be the same size");
#ifdef EL_CACHE_WARNINGS
if( A.Width() != 1 && A.Grid().Rank() == 0 )
{
cerr <<
"axpy_contract::PartialColScatterUpdate potentially causes a large "
"amount of cache-thrashing. If possible, avoid it by forming the "
"(conjugate-)transpose of the [UGath,* ] matrix instead."
<< endl;
}
#endif
if( B.ColAlign() % A.ColStride() == A.ColAlign() )
{
const Int colStride = B.ColStride();
const Int colStridePart = B.PartialColStride();
const Int colStrideUnion = B.PartialUnionColStride();
const Int colRankPart = B.PartialColRank();
const Int colAlign = B.ColAlign();
const Int height = B.Height();
const Int width = B.Width();
const Int localHeight = B.LocalHeight();
const Int maxLocalHeight = MaxLength( height, colStride );
const Int recvSize = mpi::Pad( maxLocalHeight*width );
const Int sendSize = colStrideUnion*recvSize;
//vector<T> buffer( sendSize );
vector<T> buffer;
buffer.reserve( sendSize );
// Pack
copy::util::PartialColStridedPack
( height, width,
colAlign, colStride,
colStrideUnion, colStridePart, colRankPart,
A.ColShift(),
A.LockedBuffer(), A.LDim(),
buffer.data(), recvSize );
// Communicate
mpi::ReduceScatter( buffer.data(), recvSize, B.PartialUnionColComm() );
// Unpack our received data
axpy::util::InterleaveMatrixUpdate
( alpha, localHeight, width,
buffer.data(), 1, localHeight,
B.Buffer(), 1, B.LDim() );
}
else
LogicError("Unaligned PartialColScatter not implemented");
}
