Are you actually interested in getting the result as a calendarDuration as opposed to plain duration? Indeed, for some reason sum is not implemented fo calendarDuration. It is for duration though.
I assume that you actually don't want calendarDuration, which is useful if you want to express elapsed time in terms of years, months or weeks but not so useful for ellapsed time in hours, minutes, seconds. For that you're better served with plain duration. In that case:
dt = time_end_operation_RH - time_end_operation_RH; %plain duration array
total_uptime_RH = sum(dt);
If you do want a calendarDuration result, you'll have to perform the sum in a loop:
dt = between(time_end_operation_RH, time_start_operation_RH);
total_uptime_RH = 0;
for idt = 1:numel(dt)
total_uptime_RH = total_uptime_RH + dt(idt);
end
