コーシー分布
In probability theory, a log-Cauchy distribution is a probability distribution of a random variable whose logarithm is distributed in accordance with a Cauchy distribution. If "X" is a random variable with a Cauchy distribution, then "Y" = exp("X") has a log-Cauchy distribution; likewise, if "Y" has a log-Cauchy distribution, then "X" = log("Y") has a Cauchy distribution.