This is the tgamma_lower from the boost library
lowergamma(a, z)| a | The numeric 'a' parameter in the upper incomplete gamma |
|---|---|
| z | The numeric 'z' parameter in the upper incomplete gamma |
lowergamma results
The lowergamma function is given by:
$$lowergamma(a, z) = \int_{0}^{z}t^{a-1}\cdot e^{-t} dt$$
Matthew L. Fidler
lowergamma(1, 3)
#> [1] 0.9502129
lowergamma(1:3, 3)
#> [1] 0.9502129 0.8008517 1.1536198
lowergamma(1, 1:3)
#> [1] 0.6321206 0.8646647 0.9502129