BobW - 11/28/2016 4:54 PM
You are making this too complicated. First even if the computer and the tables use the same algorithm your computer will almost always allow you more time. That is because it uses actual depths and times rather than groups of times and depths. Think of it this way if you buy a 45 dollar mask but you can only pay with twenties then you will be paying more. The tables calculate in large bills and the computer calculates in singles. Your nitrogen groups in the log are an artificial construct used by the tables to contain a range of values representing your nitrogen load. Your computer does not need or use these groups since it has recorded exact values and thus has no need for a range of values. Now as stated below computers do fail both on the surface and at depth but not often with proper care. So to prepare for a possible failure I always log max depth, down time and surface interval for each dive. That way I can always go back and reconstruct the days dives with a Table (I use the wheel for backup since it provides more granularity (and thus normally more bottom time) in addition to supporting multilevel dives).
Hope this helps.