- 873 名前：１３２人目の素数さん mailto:sage [2025/05/24(土) 21:16:24.84 ID:VetM3rz7.net]
- # dbeta(L,a,b) == dbbeta(U,a,b)
# Solve[L^(a-1)(1-L)^(b-1)==U^(a-1)(1-U)^(b-1), b]
L=1/7
U=1/5
credMass = 0.95
f = function(a) 1 + ((a - 1) * log(U / L)) / log((1 - L) / (1 - U))
g = function(a) pbeta(U,a,f(a)) - pbeta(L,a,f(a)) - credMass
(re=uniroot(g,c(1,1e5)))
curve(g(x),1,150,bty="l") ; abline(h=0,lty=3)
c(re$root,f(re$root))
