Merge pull request #4 from TSGut/main

Implement loggamma

Author: oscardssmith

README.md

@@ -4,17 +4,13 @@
 
 Simple and fast Gamma function.
 
-This library provides an implimentation of the [Gamma function](https://en.wikipedia.org/wiki/Gamma_function).
+This library provides a dependence-free, Julia native implementation of the [Gamma function](https://en.wikipedia.org/wiki/Gamma_function) and related utilities like `loggamma` and `logabsgamma`.
 
-This library is very simple with no dependencies and a single exported function: `gamma`
-
-Supports `Integer`, `Float16`, `Float32`, and `Float64` arguments.
-
-Support for `Complex` numbers, `BigFloats` and `loggamma` comming soon.
+Supports `Integer`, `Float16`, `Float32`, and `Float64`, `Complex` and `BigFloat` arguments.
 
 ## Contributing
 
 Contributions are very welcome, as are feature requests, suggestions or general discussions.
 Please open an issue for discussion on newer implementations, share papers, new features, or if you encounter any problems.
-Our goal is to provide high quality implementations of Bessel functions that match or exceed the accuracy of the implementations provided by SpecialFunctions.jl.
+Our goal is to provide high quality Julia native implementations of Gamma functions that match or exceed the accuracy of the implementations provided by SpecialFunctions.jl.
 Please let us know if you encounter any accuracy or performance issues.

src/Gamma.jl

@@ -1,8 +1,9 @@
 module Gamma
 
-include("gamma.jl")
-include("precompile.jl")
+    include("gamma_implementation.jl")
+    include("precompile.jl")
+    include("loggamma.jl")
 
-export gamma
+    export gamma, loggamma, logabsgamma, logfactorial
 
 end

src/gamma.jl src/gamma_implementation.jlsrc/gamma.jl renamed to src/gamma_implementation.jl

@@ -125,3 +125,6 @@ function gamma(n::Integer)
 end
 
 gamma_near_1(x) = evalpoly(x-one(x), (1.0, -0.5772156649015329, 0.9890559953279725, -0.23263776388631713))
+
+gamma(x::BigFloat) = exp(loggamma(x))
+gamma(x::Complex) = exp(loggamma(x))