| extval_frechet | Calculates the probability (PDF) and cumulative (CDF) distribution functions of the  Frechet Type II distribution given the shape, scale and location parameters. | 
| extval_gev | Calculates the probability (PDF) and cumulative (CDF) distribution functions of the  Generalized Extreme Value (GEV) distribution given the shape, scale and location parameters. | 
| extval_gumbel | Calculates the probability (PDF) and cumulative (CDF) distribution functions of the  Gumbel (Type I) distribution function given the scale and location parameters. | 
| extval_mlegam | Estimates the location, shape, scale and other parameters for the Gamma distribution using maximum-likelihood estimation (MLE). | 
| extval_mlegev | Estimates the shape, scale and location parameters for the Generalized Extreme-Value (GEV) distribution using Maximum-Likelihood Estimation (MLE). | 
| extval_pareto | Calculates the probability (PDF) and cumulative (CDF) distribution functions of the  Pareto distributions (Generalized, Type I, TYpe II) given the shape, scale and location parameters. | 
| extval_recurrence_table | Calculates the recurrence interval (return period), cumulative and exceedence probabilities based upon a time series. | 
| extval_return_period | Calculates the period of an event (eg, flood, heat wave, drought)  occurring given an average event recurrence interval and specified probability level. | 
| extval_return_prob | Calculates the probability of an event (eg, flood, heat wave, drought) given an average event interval and a specified exceedance period. | 
| extval_weibull | Calculates the probability (PDF) and cumulative (CDF) distribution functions of the  Weibull Type III distribution given the shape, scale and location parameters. |