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Joined 1 year ago
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Cake day: June 29th, 2023

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  • Nah, reach is a huge advantage. I’m not sure how rapier fencing differs from regulation sabre/epée/foil, but here’s my 2 cents from that perspective:

    Smaller people are not, as a rule, substantially quicker than larger. If you see any difference in your experience, it’s likely a selection bias (shorter people have to be quicker to compete at the same level). The shorter person must enter the strike range of the taller person before the taller person comes within theirs and must be significantly quicker or more skilled to overcome that dead space. If the taller person can maintain a proper distance, gg. Taller people can also lunge farther, giving a wider active range.

    Targeting is a smaller issue than you make it out to be; footwork and maintaining balance, which reposition the core, are at least as important as leaning to dodge, and advantage the taller person (longer legs = more movement range). If the taller person is coming from above as you say, they can just continue their slash (sabre) downward toward that less mobile core, or squat a bit deeper if the arc won’t reach. If instead you were referring to a poke, they’re either already targeting the torso anyway (foil) or whatever body part is most easily reachable (epée; still often torso, but cheeky wrist/arm strikes can be something of an equalizer here), and anyway they are already striking at a range that the shorter person cannot, making a successful counterattack more difficult.

    Besides reach, a height difference is brutal when it comes to sabre fencing; the shorter person is restricted to targeting arms and torso (can’t reach the head easily), so the taller person can anticipate strikes from fewer angles. The taller person can come from any direction and has gravity on their side for own overhead strikes. Those suck to defend against.



  • So many solver solutions that day, either Z3 or Gauss-Jordan lol. I got a little obsessed about doing it without solvers or (god forbid) manually solving the system and eventually found a relatively simple way to find the intersection with just lines and planes:

    1. Translate all hailstones and their velocities to a reference frame in which one stone is stationary at 0,0,0 (origin).
    2. Take another arbitrary hailstone (A) and cross its (rereferenced) velocity and position vectors. This gives the normal vector of a plane containing the origin and the trajectory of A, both of which the thrown stone must intersect. So, the trajectory of the thrown stone lies in that plane somewhere.
    3. Take two more arbitrary hailstones B and C and find the points and times that they intersect the plane. The thrown stone must strike B and C at those points, so those points are coordinates on the line representing the thrown stone. The velocity of the thrown stone is calculated by dividing the displacement between the two points by the difference of the time points of the intersections.
    4. Use the velocity of the thrown stone and the time and position info the intersection of B or C to determine the position of the thrown stone at t = 0
    5. Translate that position and velocity back to the original reference frame.

    It’s a suboptimal solution in that it uses 4 hailstones instead of the theoretical minimum of 3, but was a lot easier to wrap my head around. Incidentally, it is not too hard to adapt the above algorithm to not need C (i.e., to use only 3 hailstones) by using line intersections. Such a solution is not much more complicated than what I gave and still has a simple geometric interpretation, but I’ll leave that as an exercise for the reader :)



  • The color schemes are terrible, especially for the top two maps. The upper and lower ends of the range (dark red and dark green) are just about the worst possible choice for colorblind folks (1 person in 20!). Even ignoring that, the lightest colors are midpoints in a sequential dataset, giving the false impression of a center point from which the data diverge. This doesn’t make sense for total population, the range for which is open only at one end (minimum of zero). You could make the argument about diverging from some measure of center, but that is not indicated anywhere. A diverging color scheme would be appropriate for the third map (change in population diverges up or down from 0, or could diverge around the global change), but there again the lightest color is arbitrarily located halfway up the range.

    Here are some good examples for sequential and diverging color schemes: https://personal.sron.nl/~pault/#fig:scheme_sunset