@Override
public Matrix applySimple(SparseMatrix a, DenseMatrix b) {
Matrix result = b.multiply(-1.0);
MatrixIterator it = a.nonZeroIterator();
while (it.hasNext()) {
double x = it.next();
int i = it.rowIndex();
int j = it.columnIndex();
result.set(i, j, result.get(i, j) + x);
}
return result;
}
