Matrix basis;
{
List<Vector> vectors = new ArrayList<Vector>(sample.size() - 1);
while(iter.hasNext()) {
Vector vec = relation.get(iter.next()).getColumnVector();
vectors.add(vec.minusEquals(originV));
}
// generate orthogonal basis
basis = generateOrthonormalBasis(vectors);
if(basis == null) {
// new sample has to be taken.