P82 · Packing and covering · Classic · Hard

Equal circles in regular polygons · m = 8 · n = 39

Pack n equal circles into the regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1) so as to maximise their common radius.

Instancem = 8 · n = 39
ObjectiveMaximize circle radius

Record comparison

circle radius · Higher is better
RecordValue / intervalAuthor / holderSource
External best known[0.134962830725, 0.134962830727]Stefan ZorcicPackomania ↗
Site recordNo player record yet——

Formal definition

  • ContainerThe editor and certificate normalise the container to the exact regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1), while public scores follow the literature convention. Boundary contact is allowed.
  • SubmissionSubmit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.
  • ConstraintsExactly n congruent pieces lie wholly inside the container with pairwise disjoint interiors. Polygons may rotate independently by arbitrary angles.
  • PrecisionInput decimals are parsed as exact rationals and regular-polygon vertices are defined algebraically, with zero floating-point tolerance in feasibility checks.
  • ObjectiveMaximise the circle radius r (with container circumradius fixed at 1).
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Layout shown: starter layout

VERIFIED CONSTRUCTIONVERIFIED CONSTRUCTION

Getting a feel for it

Literature targets and coordinate certificates

Literature targets are converted at their published precision, while nine-decimal coordinate certificates are stored and displayed alongside the source values. Pentagon and hexagon rows n = 41–100 and octagon rows n = 41–48 cite Packomania's value and author without importing its coordinates; they start from an ordinary site grid baseline.

Source
The current arrangement for Equal circles in regular polygons m = 8 · n = 39
LAYOUT & HISTORY

Starter layout

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ANSWER FORMAT

How to write your answer

the regular m-gon with centre (1,1), circumradius 1, and first vertex (2,1)

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4.

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "1.002488666",
      "y": "0.147113555"
    },
    {
      "turn": "0",
      "x": "1.244304575",
      "y": "0.896024082"
    },
    {
      "turn": "0",
      "x": "1.780686034",
      "y": "0.823204121"
    },
    {
      "turn": "0",
      "x": "0.752387168",
      "y": "0.248647309"
    },
    {
      "turn": "0",
      "x": "1.098221860",
      "y": "1.248698955"
    },
    {
      "turn": "0",
      "x": "0.609975139",
      "y": "1.434186232"
    },
    {
      "turn": "0",
      "x": "0.795563484",
      "y": "0.515097432"
    },
    {
      "turn": "0",
      "x": "0.900715826",
      "y": "1.812792433"
    },
    {
      "turn": "0",
      "x": "1.418467217",
      "y": "1.680582488"
    },
    {
      "turn": "0",
      "x": "1.383234848",
      "y": "1.412966078"
    },
    {
      "turn": "0",
      "x": "1.463243530",
      "y": "0.738145659"
    },
    {
      "turn": "0",
      "x": "1.169088423",
      "y": "1.783878567"
    },
    {
      "turn": "0",
      "x": "0.212331768",
      "y": "0.840060638"
    },
    {
      "turn": "0",
      "x": "0.502613624",
      "y": "1.186530487"
    },
    {
      "turn": "0",
      "x": "0.829849262",
      "y": "1.277612822"
    },
    {
      "turn": "0",
      "x": "0.401958238",
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    },
    {
      "turn": "0",
      "x": "0.722487747",
      "y": "1.029957077"
    },
    {
      "turn": "0",
      "x": "0.470606194",
      "y": "0.918509243"
    },
    {
      "turn": "0",
      "x": "1.299836306",
      "y": "0.523301665"
    },
    {
      "turn": "0",
      "x": "1.677389955",
      "y": "0.573825327"
    },
    {
      "turn": "0",
      "x": "1.264603937",
      "y": "0.255685255"
    },
    {
      "turn": "0",
      "x": "1.133856055",
      "y": "1.516262157"
    },
    {
      "turn": "0",
      "x": "1.045664982",
      "y": "0.413563678"
    },
    {
      "turn": "0",
      "x": "1.566539609",
      "y": "0.987524452"
    },
    {
      "turn": "0",
      "x": "1.637406172",
      "y": "1.522704064"
    },
    {
      "turn": "0",
      "x": "1.347600654",
      "y": "1.145402876"
    },
    {
      "turn": "0",
      "x": "1.602173803",
      "y": "1.255087654"
    },
    {
      "turn": "0",
      "x": "0.315627847",
      "y": "0.590681844"
    },
    {
      "turn": "0",
      "x": "0.573902273",
      "y": "0.669130449"
    },
    {
      "turn": "0",
      "x": "0.191300644",
      "y": "1.109165738"
    },
    {
      "turn": "0",
      "x": "0.294596723",
      "y": "1.358544532"
    },
    {
      "turn": "0",
      "x": "0.865483457",
      "y": "1.545176023"
    },
    {
      "turn": "0",
      "x": "0.992041693",
      "y": "0.999905472"
    },
    {
      "turn": "0",
      "x": "1.816320229",
      "y": "1.090767323"
    },
    {
      "turn": "0",
      "x": "0.830795852",
      "y": "0.782713842"
    },
    {
      "turn": "0",
      "x": "1.080897351",
      "y": "0.681180088"
    },
    {
      "turn": "0",
      "x": "0.515045953",
      "y": "0.395451713"
    },
    {
      "turn": "0",
      "x": "0.651337032",
      "y": "1.709496355"
    },
    {
      "turn": "0",
      "x": "1.513982731",
      "y": "0.358981333"
    }
  ],
  "radius": "0.134962830"
}
Submission format and technical detailsOpen this when you are ready to prepare a JSON answer+

Instance parameters

{
  "n": 39,
  "sides": 8
}

Starter answer

{
  "placements": [
    {
      "turn": "0",
      "x": "1.002488666",
      "y": "0.147113555"
    },
    {
      "turn": "0",
      "x": "1.244304575",
      "y": "0.896024082"
    },
    {
      "turn": "0",
      "x": "1.780686034",
      "y": "0.823204121"
    },
    {
      "turn": "0",
      "x": "0.752387168",
      "y": "0.248647309"
    },
    {
      "turn": "0",
      "x": "1.098221860",
      "y": "1.248698955"
    },
    {
      "turn": "0",
      "x": "0.609975139",
      "y": "1.434186232"
    },
    {
      "turn": "0",
      "x": "0.795563484",
      "y": "0.515097432"
    },
    {
      "turn": "0",
      "x": "0.900715826",
      "y": "1.812792433"
    },
    {
      "turn": "0",
      "x": "1.418467217",
      "y": "1.680582488"
    },
    {
      "turn": "0",
      "x": "1.383234848",
      "y": "1.412966078"
    },
    {
      "turn": "0",
      "x": "1.463243530",
      "y": "0.738145659"
    },
    {
      "turn": "0",
      "x": "1.169088423",
      "y": "1.783878567"
    },
    {
      "turn": "0",
      "x": "0.212331768",
      "y": "0.840060638"
    },
    {
      "turn": "0",
      "x": "0.502613624",
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    },
    {
      "turn": "0",
      "x": "0.829849262",
      "y": "1.277612822"
    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
      "x": "0.722487747",
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    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
      "x": "1.299836306",
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    },
    {
      "turn": "0",
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    },
    {
      "turn": "0",
      "x": "1.264603937",
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    },
    {
      "turn": "0",
      "x": "1.133856055",
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    },
    {
      "turn": "0",
      "x": "1.045664982",
      "y": "0.413563678"
    },
    {
      "turn": "0",
      "x": "1.566539609",
      "y": "0.987524452"
    },
    {
      "turn": "0",
      "x": "1.637406172",
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    },
    {
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    },
    {
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    },
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    },
    {
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    },
    {
      "turn": "0",
      "x": "0.191300644",
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    },
    {
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      "x": "0.294596723",
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    },
    {
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      "x": "0.865483457",
      "y": "1.545176023"
    },
    {
      "turn": "0",
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    },
    {
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    },
    {
      "turn": "0",
      "x": "0.830795852",
      "y": "0.782713842"
    },
    {
      "turn": "0",
      "x": "1.080897351",
      "y": "0.681180088"
    },
    {
      "turn": "0",
      "x": "0.515045953",
      "y": "0.395451713"
    },
    {
      "turn": "0",
      "x": "0.651337032",
      "y": "1.709496355"
    },
    {
      "turn": "0",
      "x": "1.513982731",
      "y": "0.358981333"
    }
  ],
  "radius": "0.134962830"
}

Submit {radius, placements:[{x,y,turn},…]}, with each value written as a decimal string of at most nine places. Here x, y are centre coordinates; circles require turn = 0 and polygons use turn = tan(θ/2). Coordinates and turn must lie in [−4, 4], with 0 < radius ≤ 4. · Verifier v1.0.0

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