docs: SparseMatrix normalized(SparseMatrix matrix) {
  		int ySize = matrix.size()[1];
  		float ySum[] = new float[ySize];
  		TLongFloatIterator it = matrix.vector.iterator();
  		for (int i = matrix.vector.size(); i-- > 0;) {
  			it.advance();
  			ySum[matrix.getIndices(it.key())[1]] += it.value();
  		}
  		it = matrix.vector.iterator();
  		for (int i = matrix.vector.size(); i-- > 0;) {
  			it.advance();
  			matrix.set(it.key(), it.value()
  					/ (ySum[matrix.getIndices(it.key())[1]] + eps));
  		}
  		return matrix;
  	}