teaching machines

IEEE-754 sighting

January 11, 2011 by . Filed under pop computer science, public.

I was walking through our local transit system’s headquarters yesterday when I saw what I presumed was someone dividing 0 by 0 in the marquee software:

NaN means Not A Number in IEEE-754 floating point standard speak.

When I showed my non-programming wife, she politely chuckled and moved on with her business. On questioning, she confessed she didn’t think much of it — just a cute message to DAD on a marquee that had slipped down. Of course, she was right. What I thought were Ns in NAN look nothing like the Ns in the top line. And I’d seen this message and the corresponding one to MOM hundreds of times! I guess this is what one’s focus does to oneself.