code: @Override
      public double probability(double x0, double x1) throws NumberIsTooLargeException {
          if (x0 > x1) {
              throw new NumberIsTooLargeException(LocalizedFormats.LOWER_ENDPOINT_ABOVE_UPPER_ENDPOINT, x0, x1, true);
          }
          final double denom = standardDeviation * SQRT2;
          final double v0 = (x0 - mean) / denom;
          final double v1 = (x1 - mean) / denom;
          return 0.5 * Erf.erf(v0, v1);
      }
docs: {@inheritDoc}