code: function fastSimilarity(newPeaks2, from, to) {
      array1Extract = extract(array1, from, to);
      array2Extract = newPeaks2;
      if (common & COMMON_SECOND) array1Extract = getCommonArray(array1Extract, array2Extract, widthBottom);
      normalize(array1Extract);
      var diff = calculateDiff();
      return calculateOverlapFromDiff(diff);
    }
docs: /*
  This works mainly when you have a array1 that is fixed
  newPeaks2 have to be normalized ! (sum to 1)