beta_inv()beta_inv()

返回 beta 累积概率 beta 密度函数的反函数。Returns the inverse of the beta cumulative probability beta density function.

beta_inv(0.1, 10.0, 50.0)

probability = beta_cdf(x,...),则 beta_inv(probability,...) = xIf probability = beta_cdf(x,...), then beta_inv(probability,...) = x.

在项目计划中,给定预期完成时间和可变性,可以使用 beta 分布对可能的完成时间进行建模。The beta distribution can be used in project planning to model probable completion times given an expected completion time and variability.

语法Syntax

beta_inv(probability, alpha, beta)beta_inv(probability, alpha, beta)

参数Arguments

  • probability:与 beta 分布相关的概率。probability: A probability associated with the beta distribution.
  • alpha:分布的一个参数。alpha: A parameter of the distribution.
  • beta:分布的一个参数。beta: A parameter of the distribution.

返回Returns

  • beta 累积概率密度函数 beta_cdf() 的反函数The inverse of the beta cumulative probability density function beta_cdf()

说明Notes

如果任何参数不是数字,则 beta_inv() 将返回 null 值。If any argument is nonnumeric, beta_inv() returns null value.

如果 alpha ≤ 0 或 beta ≤ 0,则 beta_inv() 将返回 null 值。If alpha ≤ 0 or beta ≤ 0, beta_inv() returns the null value.

如果 probability ≤ 0 或 probability > 1,beta_inv() 将返回 NaN 值。If probability ≤ 0 or probability > 1, beta_inv() returns the NaN value.

给定 probability 值后,beta_inv() 会寻找值 x,使得 beta_cdf(x, alpha, beta) = probability。Given a value for probability, beta_inv() seeks that value x such that beta_cdf(x, alpha, beta) = probability.

示例Examples

datatable(p:double, alpha:double, beta:double, comment:string)
[
    0.1, 10.0, 20.0, "Valid input",
    1.5, 10.0, 20.0, "p > 1, yields null",
    0.1, double(-1.0), 20.0, "alpha is < 0, yields NaN"
]
| extend b = beta_inv(p, alpha, beta)
pp alphaalpha betabeta commentcomment bb
0.10.1 10 个10 20 个20 有效输入Valid input 0.2264150223887490.226415022388749
1.51.5 10 个10 20 个20 p > 1,产生 nullp > 1, yields null
0.10.1 -1-1 20 个20 alpha < 0,产生 NaNalpha is < 0, yields NaN NaNNaN

另请参阅See also

  • 关于计算累积 beta 分布函数,请参阅 beta-cdf()For computing cumulative beta distribution function, see beta-cdf().
  • 关于计算概率 beta 密度函数,请参阅 beta-pdf()For computing probability beta density function, see beta-pdf().