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07 Apr 2010, 18:05
Andy Lester (18 posts)

The April 2010 issue is now available at What do you think?

07 Apr 2010, 19:05
Brian Tarbox (41 posts)

I liked Mike Taylor’s article very much, in part because it leads to a question? How do we as senior members of our field teach this? His Radius of Comprehension sounds a lot like the principal of least surprise. When I learned RSX-11M+ assembly language lo those many years ago I saw that after learning one instruction I could guess most of the other instructions because they all did what you would expect them to. So how do we teach this to our more junior co-workers? I have an idea or two but what do others think?

08 Apr 2010, 17:28
Matt Siders (1 post)

Michael, you got some ‘splaining to do!

bq. You wake up. The first light of dawn is coming in the window. You glance at the clock. 5:45. You close your eyes and count off what you think is 15 seconds. You’re pretty good at this; in 15 seconds you’re not going to be off by an appreciable amount. You open your eyes and glance at the clock again. Still 5:45. What is your best guess for the current time, to a tenth of a second? 5:45:37.5.

08 Apr 2010, 20:56
Michael Swaine (69 posts)


Right you are. Here’s one attempt:

The second time you glance at the clock, you know for sure that the time is somewhere between 5:45:15 and 5:46. You know that because (1) the clock read 5:45 exactly 15 seconds ago, so it’s at least 5:45:15 now, and (2) it still reads 5:45, so the present time may be as late as a nanosecond before 5:46.

And that’s all you know. So your best guess is the midpoint of the interval [5:45:15..5:46:00), which is 5:45:37.5.

At least that’s how I figure it. I’m happy to entertain arguments in support of other answers. Or even other arguments in support of this answer. I think a Bayesian statistical approach would yield the same result, but I confess I haven’t tested that.


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