(42S) Probability of Same Birthday Day

[ijabbott]

(12-06-2018 04:32 AM)Valentin Albillo Wrote:  

(12-05-2018 11:46 PM)ijabbott Wrote:  The generalised birthday problem (probability of at least n people in a group sharing a birthday) is a lot harder. Probably intractable on a HP-42S. (Now there's a challenge!)

Intractable on a 42S?

Birthday problem generalizations

V.

Specifically, the Multiple Birthday Problem. You may be able to get approximate results (up to about 3 decimal places) using Levin's approach mentioned in that paper, but a combinatorial approach blows up too quickly as n increases, rendering it unsuitable for computation on a HP 42S.

I did knock up a program in C++ (but really C style but using C++ for convenence) using the GNU Multiple Precision library (which is a PITA to use in C, hence the use of C++ for convenience) to generate exact probabilities a while ago, although I'm not proud of it as the calculations are far from optimal (too many repeated sub calculations). Anyway, here is is: ian-abbott/birthdays.cpp (raw).

(12-06-2018 05:54 AM)Joe Horn Wrote:  The probability of being born on February 29th is NOT zero. The above document seems to utterly ignore leap year babies.

Assume a spherical cow.