code: @Pure
      public static double random(double mean, double standardDeviation) throws MathException {
          return StochasticGenerator.generateRandomValue(new GaussianStochasticLaw(mean, standardDeviation));
      }
docs: Replies a random value that respect
  the current stochastic law.
  
  @param mean is the mean of the normal distribution.
  @param standardDeviation is the standard deviation associated to the nromal distribution.
  @return a value depending of the stochastic law parameters
  @throws MathException when error in mah definition.