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Mark Nelson

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Cool Bugs

September 22, 2008

I've created a few posts here on bugs of one type or another, usually with the goal of illustrating a point.

Today's bug doesn't illustrate a point though. I just thought it was too cool to not take note of.

Weather Report Does Modular Arithmetic

Checking the weather on the Dallas Morning News web site today, I clicked to the full map to see what kind of temperatures I could expect when I got home from work. (Being late September in Texas, it is unfortunately a rather balmy 85 degrees or so.)

The little box that shows the projected temperatures throughout the day is shown below. As you can see, it starts somewhere in the current hour, and steps ahead three hours at a time:

Excerpt from Dallas Morning News Weather page

 I've circled the beauty part: a step from 8 pm to what should be 11 pm. But for some reason which I can't figure out, the time show is actually -1 am.

Of course, as any programmer will readily admit, -1 am is 11 pm. But I'm not sure the average weather map reader is going to be able to figure that out.

I don't see any obvious way to write this bug. Anyone have a plausible scenario?

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