Explain xkcd: It's 'cause you're dumb.
Title text: In lieu of mapping software, I once wrote a Perl program which, given a USB GPS receiver and a destination, printed 'LEFT' 'RIGHT' OR 'STRAIGHT' based on my heading.
GPS is a system allowing people to find their location and speed on Earth. It was first developed for the U.S. military, but now it sees international usage for everyday navigation. Many motorists today have GPS devices (sometimes just called GPS's) that can give driving directions electronically.
"Hot and Cold" refers to a children's game. The goal is to identify a random object in the room, aided by another who can only give two directions: "hot" (you're getting closer to the target), and "cold" (you're moving away from the target). These are also somewhat absolute measurements, so "hot" or "warm" could also mean proximity to the target — look, give 'em a break, it's a kids' game, what do they know about scalar fields‽ Anyways, Cueball's "cheap GPS" unhelpfully emulates this game with hilarious results.
The series of instructions spoken ("cold", "warm", "hot", then "cold" again) suggests that Cueball either missed a turn, or that he just passed his destination.
Randall describes a past engineering project of his that can only describe turns "as the crow flies." So, for example, if he was driving north with the destination to the northeast, the GPS would tell him to turn right even if no such turn was legally possible. Perhaps not very functional, but it is a pretty cool thing to build.
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- [Cueball driving down the road, with a GPS reading "COLD".]
- GPS: COLD... WARM... HOT! COLD...
In an inversion of Title-text, I did actually make a Perl script for Geohashing which (for a given target) gave a bearing and distance to target from the interogated GPS USB dongle's idea of my current location... But the bearing was absolute, with no way of determining which relative direction I (or at least the laptop/dongle) was facing. (I had decided that direction of travel could not be reliably worked out from the last pair or trio of locations, given that when it mattered most I was probably tramping quickly back and forth over moorland looking for some specific feature of vegetation or drainage matching up with the aerial photos). Examination of moss on stones or trees (or satellite TV dishes on houses, for the urban environment) was occasionally needed to narrow down orientation. Or approximating the old analogue watch-hands trick with the sun, in my head (having only the digital time). 184.108.40.206 00:13, 18 June 2013 (UTC)
 Hit the pot
Is the game Topfschlagen known outside Germany? There is only a German entry on wikipedia (as of today). For me this kind of game is actually also the first thing that came to mind. Usually besides hot/cold ("heiß", "warm"/"kalt") comparative forms of these adjectives are used to indicate the current direction: e.g. warmer ("wärmer") if the seeker currently gets closer to the goal. --Chtz (talk) 21:39, 15 July 2013 (UTC)
- I actually don't know, but this forum entry on the leo.org dictionary site confirms that the cold/hot scale is used in games in English, too, so I thought it was worth mentioning at least one of them. If someone knows another such game that is better known internationally, feel free to substitute that. --Das-g (talk) 20:48, 29 July 2013 (UTC)
- The concept comes up in various games, although I can't quite pinpoint exactly where it came from. My earliest memory of anything of that sort is an Easter egg hunt. --Quicksilver (talk) 04:29, 21 August 2013 (UTC)
- Hot and Cold does not need a special explain, everybody knows. So, my latest explain should be enough.--Dgbrt (talk) 19:54, 23 August 2013 (UTC)