c.add(r);
c = c.add(r);
  private Instances splitCenter(Random random,			        Instance center,			        double variance,			        Instances model) throws Exception {    m_NumSplits++;    AlgVector r = null;    Instances children = new Instances(model, 2);    if (m_DebugVektorsFile != null) {      Instance nextVektor = getNextDebugVektorsInstance(model);      PFD(D_RANDOMVEKTOR, "Random Vector from File " + nextVektor);      r = new AlgVector(nextVektor);    }    else {      // random vector of length = variance      r = new AlgVector(model, random);    }    r.changeLength(Math.pow(variance, 0.5));    PFD(D_RANDOMVEKTOR, "random vector *variance "+ r);        // add random vector to center    AlgVector c = new AlgVector(center);    AlgVector c2 = (AlgVector) c.clone();    c.add(r);    Instance newCenter = c.getAsInstance(model, random);    children.add(newCenter);    PFD(D_FOLLOWSPLIT, "first child "+ newCenter);        // substract random vector to center    c2.substract(r);    newCenter = c.getAsInstance(model, random);    children.add(newCenter);    PFD(D_FOLLOWSPLIT, "second child "+ newCenter);    return children;  }