{({⊃(,,⍤0)/↓(⌽@1)2(2÷⍨≢⍵)⍴⍵}⍣{⍺≡w})w←2(⊥⍣¯1)⍵}201
⍣
dfns.traj
{i←0 ⋄ i⊣{i+←1 ⋄ one_iteration}⍣{end_condition} start_value}
i
2|≢⍵
2 ¯1⍴
⍴
traj
trajectory
M⍋s⊤∊r⍳ng Dy⍋⌊○g ⍋P⌊
{P5.G.ln {(2○⍵),1○⍵}1 k×⍵×a}¨⍳n
ln
x1 y1 x2 y2 …
x1 x2 y1 y2
{P5.G.ln 30×{(2○⍵),1○⍵}1 k×⍵×a}
n
k
¨
↑
30+
{P5.G.ln {⍵○1 k×⍵×a}¨2 1}
[x1 x2 ⋄ y1 y2]
[x1 y1 ⋄ x2 y2]
⍵
{P5.G.ln↑30+{(2○⍵),1○⍵}¨1 k×⍵×a}
30×
{(2○⍵),1○⍵}
2 1∘○¨
a←2×○÷n
2 1○ᑈ
30+30×
30×1+
1
'center'P5.G.circle 30 30 60 60
2×○÷k
60
P5.G.circle 3⍴30
{n←⍺⋄P5.G.circle 3⍴30⋄{P5.G.ln↑30×1+2 1○ᑈ1n×⍵×2×○÷k}¨⍳k←⍵}