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cobin (version 1.0.1.3)

dcobin: Density function of cobin (continuous binomial) distribution

Description

Continuous binomial distribution with natural parameter \(\theta\) and dispersion parameter \(1/\lambda\), in short \(Y \sim cobin(\theta, \lambda^{-1})\), has density $$ p(y; \theta, \lambda^{-1}) = h(y;\lambda) \exp(\lambda \theta y - \lambda B(\theta)), \quad 0 \le y \le 1 $$ where \(B(\theta) = \log\{(e^\theta - 1)/\theta\}\) and \(h(y;\lambda) = \frac{\lambda}{(\lambda-1)!}\sum_{k=0}^{\lambda} (-1)^k {\lambda \choose k} \max(0,\lambda y-k)^{\lambda-1}\). When \(\lambda = 1\), it becomes continuous Bernoulli distribution.

Usage

dcobin(x, theta, lambda, log = FALSE)

Value

density of \(cobin(\theta,\lambda^{-1})\)

Arguments

x

num (length n), between 0 and 1, evaluation point

theta

scalar or length n vector, num (length 1 or n), natural parameter

lambda

scalar or length n vector, integer, inverse of dispersion parameter

log

logical (Default FALSE), if TRUE, return log density

Details

For the evaluation of \(h(y;\lambda)\), see ?cobin::dIH.

Examples

Run this code

xgrid = seq(0, 1, length = 500)
plot(xgrid, dcobin(xgrid, 0, 1), type="l", ylim = c(0,3)) # uniform 
lines(xgrid, dcobin(xgrid, 0, 3))
plot(xgrid, dcobin(xgrid, 2, 3), type="l")
lines(xgrid, dcobin(xgrid, -2, 3))

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