SigmaSwiftStatistics

Functions are designed to match results from Microsoft Excel and R, ensuring consistency for users familiar with these tools, as shown in the README for functions like average and standard deviation.

Includes a wide range of statistical functions from mean to nine quantile methods, covering most common descriptive statistics needs in Swift apps, as listed in the README with over 20 functions.

Returns nil for empty arrays or invalid inputs, preventing crashes and ensuring safe usage in production code, exemplified in functions like average and standard deviation.

Implements nine quantile calculation methods from the Hyndman and Fan paper, providing flexibility for different statistical requirements, detailed in the quantiles section.