code: public void setStandardDeviations(double devs)
      {
          if(devs <= 0 || Double.isInfinite(devs) || Double.isNaN(devs))
              throw new ArithmeticException("The stnd devs must be a positive value");
          ((Normal)getDistribution()).setStndDev(devs);
      }
docs: Sets the standard deviations used for the normal distribution
  @param devs the standard deviations to set