weibullparinv.r

来自「这个包里面含有利用极大似然估计方法来拟合成组数据和条件数据的有限混合分布模型的函」· R 代码 · 共 18 行

## last modified June 2002

weibullparinv <- function(shape, scale, loc = 0) 
{
    nu <- 1/shape
    if (nu < 1e-6) {
        mu <- scale * (1 + nu * digamma(1) + nu^2 * (digamma(1)^2 + 
            trigamma(1))/2)
        sigma <- scale^2 * nu^2 * trigamma(1)
    }
    else {
        mu <- loc + gamma(1 + (nu)) * scale
        sigma <- sqrt(gamma(1 + 2 * nu) - (gamma(1 + nu))^2) * 
            scale
    }
    data.frame(mu, sigma, loc)
}