gchick: Small furry animal wearing a tin-foil hat (Default)
gchick ([personal profile] gchick) wrote in [community profile] intro_to_cs 2009-12-06 09:52 pm (UTC)

Lecture 5, abridged

(just in case anyone is feeling a little bogged down)

The first 25 minutes of lecture 5 is about how computers deal internally with numbers. Especially real numbers (the ones with decimal places). Especially really long ones.

If you're interested in this stuff for your own fun, it's actually kinda cool.

If you're not, the takeaway lesson is: sometimes you get really fucked-up-looking results, like if you take the square root of a number and then square it again and get back something that's not exactly the number you started with. If you need to count something, just use integers in the first place.

Also, Dr. Guttag is not as much fun as Dr. Grimson, and ***SPOILER*** he's trying to make the same goofy Harvard jokes, but lecturing to an empty room. This DOES NOT GO WELL FOR HIM.

So.

The second half of the lecture, from minute 25 onward, gets back to actual interesting stuff. He introduces an incredibly awesome technique (which we'll see more of in the next lecture) that's really good for things like searching and sorting *without* having to search through every single possibility like we've been doing.

Behold the amazing power of binary search!

So anyway, skip past the first half, or put it on in the background while you're doing something else.

(Also, is this helpful for people? I'd be happy to do more digested lectures; I know it's easier for me sometimes to know what point in the video I need to go back to.)

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