Archive for the 'Bad Software' category

The Excel 65,535=100,000 Bug

Oct 02 2007 Published by under Bad Software

I've been getting a lot of requests from people to talk about the recent Excel bug. For those of
you who haven't heard about this, in Excel 2007, floating point calculations that should result in
a number very, very close to either 65,535 or 65,536 are displaying their result as 100,000.
It's only in the display though - the underlying number is actually represented correctly, so if you subtract 2 from 65,536, you'll get the correct answer of 65,534 - not 99,998.

I can't give you the specifics - because without seeing the Excel code, I can't tell exactly what they got wrong. But I've got some pretty good suspicions, so I'll do my best to explain the background that leads to the problem, and what I think is probably going on. (Another excellent explanation if this
is in the Wolfram blog post that I mentioned in my fast arithmetic fractals post this weekend.)

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Granville Sewell: Genius or Liar?

Sep 26 2007 Published by under Bad Physics, Bad Software, Intelligent Design

As of 2/24/2008, Sewell has just responded to this, pretending that he just noticed it. To make discussions easier to follow, I have responded with a new post here, and I would appreciate it if comments could be posted there, to keep it all in one place.

My SciBling Mark Hofnagle over at the Denialist blog wanted me to take a look at the pseudo-mathematical ramblings of Granville Sewell. It actually connects with some of the comments in the thread about the paper by Dembski and Marks - Sewell uses part of the article to make the same kind of quantum nonsense claims that showed up here.

Sewell claims to have written a simulator which simulates the Universe, and is complaining that his supposed simulation didn't produce things like computers or aircraft carriers. I say claims because I'm pretty convinced that he did no such thing. Actually programming a simulator like the simplest of the several he claims to have done, which produces the results that he claims it produced, would be an absolutely astonishing feat of programming, involving a quantity of data that's more on the scale of Google than on the scale of Granville Sewell's laptop.

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Bad Software Design: Getting the Level Wrong

May 05 2007 Published by under Bad Software

I came across a link to an excellent article that provides an example of one of my professional bugaboos: the truly awful way that we often design software in terms of how the implementer thinks of it, instead of how the user will think of it.

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