code: public static double[] getEvenlySpacedRanks(final int n) {
      if (n <= 0) {
        throw new SketchesArgumentException("n must be > 0");
      }
      final double[] fractions = new double[n];
      fractions[0] = 0.0;
      for (int i = 1; i < n; i++) {
        fractions[i] = (double) i / (n - 1);
      }
      if (n > 1) {
        fractions[n - 1] = 1.0;
      }
      return fractions;
    }
docs: Compute an array of evenly spaced normalized ranks from 0 to 1 inclusive.
  A value of 1 will result in [0], 2 will result in [0, 1],
  3 will result in [0, .5, 1] and so on.
  @param n number of ranks needed (must be greater than 0)
  @return array of ranks