半正态分布

拟合和计算半正态分布，生成该分布的随机样本

函数

`makedist`	Create probability distribution object
`fitdist`	对数据进行概率分布对象拟合
`distributionFitter`	Open Distribution Fitter app

`cdf`	累积分布函数
`icdf`	Inverse cumulative distribution function
`iqr`	Interquartile range
`mean`	Mean of probability distribution
`median`	Median of probability distribution
`negloglik`	Negative loglikelihood of probability distribution
`paramci`	Confidence intervals for probability distribution parameters
`pdf`	概率密度函数
`proflik`	Profile likelihood function for probability distribution
`random`	Random numbers
`std`	Standard deviation of probability distribution
`truncate`	Truncate probability distribution object
`var`	Variance of probability distribution