docs: public void sortByEigenValue(Comparator<Double> cmp)
      {
          if(isComplex())
              throw new ArithmeticException("Eigen values can not be sorted due to complex results");
          IndexTable it = new IndexTable(DoubleList.unmodifiableView(d, d.length), cmp);
          
          for(int i = 0; i < d.length; i++)
          {
              RowColumnOps.swapCol(V, i, it.index(i));
              double tmp = d[i];
              d[i] = d[it.index(i)];
              d[it.index(i)] = tmp;
              
              it.swap(i, it.index(i));
          }
          
      }