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)
若 probability = beta_cdf(
x ,...)
,则 beta_inv(
probability ,...)
= x 。If 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().