算額(その489)
宮城県丸森町小斎日向 鹿島神社 大正年間
徳竹亜紀子,谷垣美保: 2021年度の算額調査,仙台高等専門学校名取キャンパス 研究紀要,第 58 号, p.7-28, 2022.
https://www.sendai-nct.ac.jp/natori-library/wp/wp-content/uploads/2022/03/kiyo2022-2.pdf
算額の破損のため,図以外の情報は殆どない。
外円を 3 本の弦で 5 個の領域に区切り,各領域に 甲円 2 個,乙円 3 個が入っている。
外円の半径と中心座標を r0, (0, 0); 一般性を失わずに r0 = 1 と設定できる。
甲円の半径と中心座標を r1, (x1, y1)
中円の半径と中心座標を r2, (0, r0 - r2), (0, 3r2 - r0), (0, r2 - r0)
右上がりの斜線と外円の交点座標を (sqrt(r0^2 - b^2), b)
とおき,以下の連立方程式を解く。
include("julia-source.txt");
using SymPy
@syms b::positive, r0::positive, r1::positive,
x1::positive, y1::positive, r2::positive;
r0 = 1
eq1 = x1^2 + y1^2 - (r0 - r1)^2
eq2 = distance(sqrt(r0^2 -(2r2 - r0)^2), 2r2 - r0, -sqrt(r0^2 - b^2), b, x1, y1) - r1^2
eq3 = distance(-sqrt(r0^2 -(2r2 - r0)^2), 2r2 - r0, sqrt(r0^2 - b^2), b, x1, y1) - r1^2
eq4 = distance(sqrt(r0^2 -(2r2 - r0)^2), 2r2 - r0, -sqrt(r0^2 - b^2), b, 0, 3r2 - r0) - r2^2
eq5 = distance(sqrt(r0^2 -(2r2 - r0)^2), 2r2 - r0, -sqrt(r0^2 - b^2), b, 0, r0 - r2) - r2^2;
# res = solve([eq1, eq2, eq3, eq4, eq5], (b, r1, x1, y1, r2))
using NLsolve
function nls(func, params...; ini = [0.0])
if typeof(ini) <: Number
r = nlsolve((vout, vin) -> vout[1] = func(vin[1], params..., [ini]), ftol=big"1e-40")
v = r.zero[1]
else
r = nlsolve((vout, vin)->vout .= func(vin, params...), ini, ftol=big"1e-40")
v = r.zero
end
return v, r.f_converged
end;
function H(u)
(b, r1, x1, y1, r2) = u
x = sqrt(1 - b^2)
y = sqrt(1 - r2)
z = sqrt(r2)
return [
x1^2 + y1^2 - (1 - r1)^2, # eq1
-r1^2 + (x1 - (x1*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1) - (b - 2*r2 + 1)*(-2*b^2*z*y + b^2*x1 + 4*b*r2^(3/2)*y + 2*b*z*y1*y - 2*b*z*y - 4*b*r2*x1 - 2*b*r2*x + 2*b*x1 + b*y1*x + b*x - 4*r2^(3/2)*y1*y + 2*z*y1*y + 4*r2^2*x1 + 4*r2^2*x - 4*r2*x1 - 2*r2*y1*x - 4*r2*x + x1 + y1*x + x)/2)/(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1))^2 + (y1 - (y1*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1) - (x + sqrt(1 - (2*r2 - 1)^2))*(-2*b^2*z*y + b^2*x1 + 4*b*r2^(3/2)*y + 2*b*z*y1*y - 2*b*z*y - 4*b*r2*x1 - 2*b*r2*x + 2*b*x1 + b*y1*x + b*x - 4*r2^(3/2)*y1*y + 2*z*y1*y + 4*r2^2*x1 + 4*r2^2*x - 4*r2*x1 - 2*r2*y1*x - 4*r2*x + x1 + y1*x + x)/2)/(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1))^2, # eq2
-r1^2 + (x1 - (x1*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1) - (b - 2*r2 + 1)*(2*b^2*z*y + b^2*x1 - 4*b*r2^(3/2)*y - 2*b*z*y1*y + 2*b*z*y - 4*b*r2*x1 + 2*b*r2*x + 2*b*x1 - b*y1*x - b*x + 4*r2^(3/2)*y1*y - 2*z*y1*y + 4*r2^2*x1 - 4*r2^2*x - 4*r2*x1 + 2*r2*y1*x + 4*r2*x + x1 - y1*x - x)/2)/(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1))^2 + (y1 - (y1*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1) + (x + sqrt(1 - (2*r2 - 1)^2))*(2*b^2*z*y + b^2*x1 - 4*b*r2^(3/2)*y - 2*b*z*y1*y + 2*b*z*y - 4*b*r2*x1 + 2*b*r2*x + 2*b*x1 - b*y1*x - b*x + 4*r2^(3/2)*y1*y - 2*z*y1*y + 4*r2^2*x1 - 4*r2^2*x - 4*r2*x1 + 2*r2*y1*x + 4*r2*x + x1 - y1*x - x)/2)/(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1))^2, # eq3
-r2^2 + (b - 2*r2 + 1)^2*(2*b^2*z*y - 10*b*r2^(3/2)*y + 4*b*z*y - b*r2*x + 12*r2^(5/2)*y - 10*r2^(3/2)*y + 2*z*y + 2*r2^2*x - r2*x)^2/(4*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1)^2) + (3*r2 - 1 - (b^3*r2 + 2*b^2*z*x*y - 18*b^2*r2^2 + 15*b^2*r2 - 2*b^2 + 44*b*r2^3 - 60*b*r2^2 + 27*b*r2 - 4*b - 8*r2^(5/2)*x*y + 8*r2^(3/2)*x*y - 2*z*x*y - 24*r2^4 + 44*r2^3 - 34*r2^2 + 13*r2 - 2)/(2*(-2*b^2*r2 + b^2 + 2*b*z*x*y + 4*b*r2^2 - 4*b*r2 + 2*b - 4*r2^(3/2)*x*y + 2*z*x*y - 2*r2 + 1)))^2, # eq4
-r2^2 + (-r2 + 1 - (b^3*z*y + 5*b^2*r2^(3/2)*y - 3*b^2*z*y + 3*b^2*r2*x/2 - b^2*x + 2*b*r2^(3/2)*y - 3*b*z*y + 2*b*r2^2*x - b*r2*x - b*x + 4*r2^(7/2)*y - 8*r2^(5/2)*y + r2^(3/2)*y + z*y + 6*r2^3*x - 10*r2^2*x + 7*r2*x/2)/(2*b^2*z*y + 4*b*r2^(3/2)*y - 2*b*z*y + 2*b*r2*x - b*x - 4*z*y + 4*r2^2*x - 4*r2*x - x))^2 + (3*b^3*r2/2 - b^3 - b^2*z*x*y - b^2*r2^2 + 3*b^2*r2/2 - b^2 - 2*b*r2^(3/2)*x*y + 2*b*z*x*y - 2*b*r2^3 + 2*b*r2^2 - 3*b*r2/2 + b + 8*r2^(5/2)*x*y - 10*r2^(3/2)*x*y + 3*z*x*y - 4*r2^4 + 10*r2^3 - 5*r2^2 - 3*r2/2 + 1)^2/(2*b^2*z*y + 4*b*r2^(3/2)*y - 2*b*z*y + 2*b*r2*x - b*x - 4*z*y + 4*r2^2*x - 4*r2*x - x)^2, # eq5
]
end;
r0 = 1
iniv = BigFloat[0.77, 0.32, 0.55, 0.3, 0.31]
res = nls(H, ini=iniv)
(BigFloat[0.7784615384615384615384615384615384615384615384615384615384616011678188086041049, 0.3461538461538461538461538461538461538461538461538461538461544534842427177340537, 0.576923076923076923076923076923076923076923076923076923076925033822024574673162, 0.3076923076923076923076923076923076923076923076923076923076934100784216705502225, 0.3076923076923076923076923076923076923076923076923076923076922943346533297705356], true)
b = 0.778462; r1 = 0.346154; x1 = 0.576923; y1 = 0.307692; r2 = 0.307692
using Plots
function draw(more)
pyplot(size=(500, 500), grid=false, aspectratio=1, label="", fontfamily="IPAMincho")
r0 = 1
(b, r1, x1, y1, r2) = res[1] #[17.0, 29, 16, 16.4]
@printf("b = %g; r1 = %g; x1 = %g; y1 = %g; r2 = %g\n",
b, r1, x1, y1, r2)
plot()
circle(0, 0, r0, :blue)
circle(x1, y1, r1, :green)
circle(-x1, y1, r1, :green)
circle(0, r0 - r2, r2, :red)
circle(0, 3r2 - r0, r2, :red)
circle(0, r2 - r0, r2, :red)
segment(-sqrt(r0^2 - (2r2 - r0)^2), 2r2 - r0, sqrt(r0^2 - (2r2 - r0)^2), 2r2 - r0, :gray)
segment(-sqrt(r0^2 - (2r2 - r0)^2), 2r2 - r0, sqrt(r0^2 - b^2), b, :gray)
segment( sqrt(r0^2 - (2r2 - r0)^2), 2r2 - r0, -sqrt(r0^2 - b^2), b, :gray)
if more
delta = (fontheight = (ylims()[2]- ylims()[1]) / 500 * 10 * 2) /3 # size[2] * fontsize * 2
hline!([0], color=:black, lw=0.5)
vline!([0], color=:black, lw=0.5)
point(x1, y1, "甲円:r1,(x1,y1)", :green, :center, delta=-delta)
point(0, r0 - r2, " 乙円:r2,(0,r0-r2)", :red, :left, :vcenter)
point(0, 3r2 - r0, " 乙円:r2,(0,3r2-r0)", :red, :left, :vcenter)
point(0, r2 - r0, " 乙円:r2,(0,r2-r0)", :red, :left, :vcenter)
point(0, r0, " r0", :blue, :left, :bottom, delta=delta/2)
point(√(r0^2 - b^2), b, "(√(r0^2-b^2),b)", :black, :center, :bottom, delta=delta)
point(√(r0^2 - (2r2 - r0)^2), 2r2 - r0, "(√(r0^2-(2r2-r0)^2),2r2-r0) ", :black, :right, :top, delta=-delta)
else
plot!(showaxis=false)
end
end;