"Passing negative values to the function is impossible because the first argument is unsigned." "impossible" is evidently an overstatement; perhaps "not allowed"? It seems there is a data typing problem. If the restriction is not going to flagged/enforced by the compiler then a check should be made at run-time. Either setting an error or returning zero. Ray
On 10/18/2012 09:52 AM, Georgios wrote: > OK, that makes sense. Thanks! > > Personally, however, I do not see a reason why the first argument must > be unsigned int, as opposed to int. The reason why I say that is that > the Poisson distribution is a distribution that gives positive > probability to non negative integers and zero to the negative ones. So > for negative int the 2 functions should return zero. That is just my > opinion though. > > Thanks again! > > On 18/10/12 14:31, Rhys Ulerich wrote: >> Hi Georgios, >> >>> Just to clarify: the function I am talking about is >>> gsl_cdf_poisson_P, Not >>> gsl_ran_poisson_pdf that I mistakenly mentioned below. The function >>> gsl_ran_poisson_pdf (unsigned int k, double mu) is fine, and >>> gsl_ran_poisson_pdf(-1,5) returns the expected zero. >> According to >> http://www.gnu.org/software/gsl/manual/html_node/The-Poisson-Distribution.html >> >> gsl_cdf_poisson_P also takes an unsigned int as the first argument. >> Passing negative values to the function is impossible because the >> first argument is unsigned. >> >> That "gsl_ran_poisson_pdf(-1,5) returns the expected zero" is mere >> happenstance. Somehow feeding the function "(unsigned) -1" == >> 4294967295 (according to my current system) is producing the zero. >> >> - Rhys > > -- My wife says I can be irritating at times. As I remember I have heard similar things from: parents, Grade school teachers, High school teachers, College Professors, College classmates, Navy supervisors, Business associates. and my children. Pshaw: what do they know?
