code: public DoubleVector getColumnVectorUnsafe(int column) {
          checkIndices(0, column);
          DoubleVector values = new DenseVector(rows.get());
          for (int row = 0; row < rows.get(); ++row) {
              AtomicVector rowEntry = getRow(row, -1, false);            
              double value = 0;
              if (rowEntry != null && (value = rowEntry.get(column)) != 0)
                  values.set(row, value);
          }
          return values;
      }
docs: Returns an immutable view of the columns's data as a non-atomic vector,
  which may present an inconsistent view of the data if this matrix is
  being concurrently modified.  This method should only be used in special
  cases where the vector is being accessed at a time when the matrix (or
  this particular row) will not be modified.