ally 0.2)

  Changes in version 1
      Ver 0 had a minor error in the final step of calculating ApEn
      because it took logarithm after summation of phi's.
      In Ver 1, I restored the definition according to original paper's
      definition, to be consistent with most of the work in the
      literature. Note that this definition won't work for Sample
      Entropy which doesn't count self-matching case, because the count 
      can be zero and logarithm can fail.

  *NOTE: This code is faster and g