5 ms·
No, IBM's estimate is for a single user. IBM figures that a typical spreadsheet user does 5000 divides per second when recalculating and does 15 minutes of reca
by kens 2y ago
No, IBM's estimate is for a single user. IBM figures that a typical spreadsheet user does 5000 divides per second when recalculating and does 15 minutes of recalculating a day. IBM also figures that the numbers people use are 90 times as likely to cause an error as Intel's uniformly-distributed numbers. The result is one user will have an error every 24 days.
- hinkley 2y agoAh. The other failure mode that occurred to me is that if a spread sheet is involved you could keep running the same calc on a bad input for months or even years when aggregating intermediate values over units of time. A problem that happens every time you run a calculation is very different from one that happens at random. Better in some ways and worse in others.
- jiggawatts 2y agoThat's also a clearly flawed analysis, because the numbers mostly don't change between re-computations of the spreadsheet cell values! E.g.: Adding a row doesn't invalidate calculations for previous rows in typical spreadsheet usage. The bug is deterministic, so repeating successful calculations over and over with the same numbers won't ever trigger the bug.
- kens 2y agoYes, the book "Inside Intel" makes the same argument about spreadsheets (p364). My opinion is that Intel's analysis is mostly objective, while IBM's analysis is kind of a scam.
- cornholio 2y agoIBM's result is correct if we interpret "one user experiences the problem every few days" as "one in a million users will experience the problem 5000 times a second, for 15 minutes every day they use the spreadsheet with certain values". It's an average that makes no sense.
- wat10000 2y agoSpreadsheets Georg....