SMPMatrixElf::MatrixT SMPMatrixElf::multiply(const MatrixT& left, const MatrixT& right)
{
if (left.empty() || right.empty()) return MatrixT();
MatrixT c(left.rows(), right.columns());
size_t elementsPerBlock = 10*10;
size_t columnsPerBlock = (size_t)ceil(sqrt(elementsPerBlock));
columnsPerBlock = min(columnsPerBlock, c.columns());
size_t rowsPerBlock = div_ceil(elementsPerBlock, columnsPerBlock);
size_t blocksPerRow = div_ceil(c.columns(), columnsPerBlock);
size_t blocksPerColumns = div_ceil(c.rows(), rowsPerBlock);
size_t blockCount = blocksPerRow * blocksPerColumns;
MatrixT transposed = right.transposed();
#pragma omp parallel for
for(size_t index=0; index<blockCount; index++)
{
size_t rowStart = (index / blocksPerRow) * rowsPerBlock;
size_t columnStart = (index % blocksPerRow) * columnsPerBlock;
size_t columnEnd = min(columnStart+columnsPerBlock, c.columns());
size_t rowEnd = min(rowStart+rowsPerBlock, c.rows());
for(size_t y=rowStart; y<rowEnd; y++)
{
for(size_t x=columnStart; x<columnEnd; x++)
{
float val = 0;
for(size_t i=0; i<left.columns(); i++)
{
val += left(y,i) * transposed(x,i);
}
c(y,x) = val;
}
}
}
return c;
}
unsigned ncol(const MatrixT& mat) {
return mat.empty() ? 0 : mat.at(0).size();
}