logDetail( "Stress collection individual probs = "
if ( _logger.isDetailEnabled() ) _logger.detail( "Stress collection individual probs = "
    double getProbability( long start_time, long end_time )    {        // The probability that a collection of stresses occurs is        // defined (here) to be the probability that at least one of        // the stresses occurs.  To find this, we assume indepdence of        // the stresses and then calculate the probability that no        // stresses occur, then taking that result and subtarcting        // from one to get the probability that at least one event        // occurs.        //        // If the set of stresses is empty, then the probability of        // nothing happening is 1.0.  Seems a little odd of aconcept,        // but it makes the math work out nicely.        //        if ( _stress_set.size() < 1 )            return 1.0;        double[] stress_prob = new double[_stress_set.size()];        Iterator stress_iter = _stress_set.iterator();        for( int stress_idx = 0; stress_iter.hasNext(); stress_idx++ )        {            StressInstance stress = (StressInstance) stress_iter.next();            stress_prob[stress_idx] = stress.getProbability( start_time,                                                             end_time );        } // while stress_iter        logDetail( "Stress collection individual probs = "                  + ProbabilityUtils.arrayToString( stress_prob ));        double prob = ProbabilityUtils.computeEventUnionProbability                ( stress_prob );                logDetail( "Stress collection total prob = " + prob );        return prob;    } // method getProbability