%N gammp %F $MIR/src/subs/gamma.for
%D Find incomplete Gamma function P(a,x)
%P nebk
%: gamma function, utilities
%B
      real function gammp (a, x)

      implicit none
      real a, x

 Find the incomplete Gamma function P(a,x)
 Algorithm from Numerical Recipes p 161

  Input
    a,x     r     Arguments
