Gammainc - incomplete gamma function
x a Gammainc -> result
2.2 1.5 Gammainc -> 0.778615
Computes the incomplete Gamma function
int(t^(a-1)*exp(-t), t=0..x) / Gamma(a)
x (double): upper limit of integration
a (double): order of Gamma function
This is the incomplete Gamma function P(a,x) defined as no. 6.5.1
in Abramowitz&Stegun. Requires the GSL.
http://sources.redhat.com/gsl/ref
H E Plesser
2001-07-26
/usr/src/packages/BUILD/sli/specialfunctionsmodule.h