adding slightly optimized gammap function
adding slightly optimized gammap function

akrawitz/jstat,smarden1/jstat,NorthDecoder/jstat,ggonzale/jstat,jstat/jstat,NorthDecoder/jstat,JeebsM/jstat,akrawitz/jstat,jstat/jstat,jamescgibson/jstat,cmpolis/jstat,JeebsM/jstat,smarden1/jstat,ggonzale/jstat