code: public LinearInterpolatedTimeDiscreteProcess add(LinearInterpolatedTimeDiscreteProcess process) throws CalculationException {
  		Map<Double, RandomVariable> sum = new HashMap<>();
  
  		for(double time: timeDiscretization) {
  			sum.put(time, realizations.get(time).add(process.getProcessValue(time, 0)));
  		}
  
  		return new LinearInterpolatedTimeDiscreteProcess(timeDiscretization, sum);
  	}
docs: Create a new linear interpolated time discrete process by
  using the time discretization of this process and the sum of this process and the given one
  as its values.
  
  @param process A given process.
  @return A new process representing the of this and the given process.
  @throws CalculationException Thrown if the given process fails to evaluate at a certain time point.