macro
poisson x lambda;
cum.

#Macro finds the Poisson or cumulative Poisson probability.

#Mathews and Malnar, Statistical Trainers and Consultants
#217 Third Street, Fairport Harbor, OH 44077
#440-350-0911   pmathews@apk.net

mconstant x lambda Px i cumPx

note
note Macro is running ...
note

if cum
   let cumPx=1		#first x is x=0
   do i=1:x			#this could be a lot faster
      call onex i lambda Px
      let cumPx=cumPx+Px
   enddo
   let cumPx=cumPx/exp(lambda)
   print cumPx
else
   call onex x lambda Px
   let Px=Px/exp(lambda)
   print Px
endif
endmacro


macro
onex x lambda Px

#This macro calculates lambda^x / x!

mconstant x lambda Px i
let Px=1
if x=0
   return
else
   do i=1:x
      let Px=Px*lambda/i
   enddo
endif
endmacro