code: @Pure
      public static double random(double k, double xmin) throws MathException {
          return StochasticGenerator.generateRandomValue(new ParetoStochasticLaw(k, xmin));
      }
docs: Replies a random value that respect
  the current stochastic law.
  
  @param k represents the shape of the distribution
  @param xmin is the minimum value of the distribution
  @return a value depending of the stochastic law parameters
  @throws MathException when error in math definition.