After a small frustration with the limitations of R 16-bit intergers. I think i have worked out a solution. The issue was i was implementing a bone-headed solution to the modulo/exponent step. So to recap. The Lehmann primality test is a probabilistic ...
Posts Tagged ‘ prime numbers ’
I may have ventured into the first circle and Virgil Is NOT Here — Lehmann Primality Test in R
So a post about Lehmann Primality Tests in HackerNews came across my twitter this morning. Seemed like a great quick coding exercise during lunch. Little Did I know…It is wonderfully simple primality test but i think i have hit up against some R quir...
Ulam Spirals in R and ggplot
Having seen a twitter post speed by about Ulam Spirals I started to read up. As the story goes in 1963 Stanislaw Ulam was bored at conference and started scribbling numbers in a spiral. What he discovered was a strange diaginal pattern of Prime Nu...
Le Monde puzzle [#6]
![Le Monde puzzle [#6]](http://feeds.wordpress.com/1.0/comments/xianblog.wordpress.com/9180/)
A simple challenge in Le Monde this week: find the group of four primes such that any sum of three terms in the group is prime and the overall sum is minimised. Here is a quick exploration by simulation, using the schoolmath package (with its imperfections): A=primes(start=1,end=53) lengthA=length(A) res=4*53 for (t in 1:10^4){ B=sample(A,4,prob=1/(1:lengthA)) sto=is.prim(sum(B)) 
bug in schoolmath
Neil Gunther has pointed out on his blog that the prime number decomposition R package schoolmath contains mistakes in the function primes, listing 1 as a prime number but also including decomposable numbers like 133 in its list of prime numbers: > primes(100,140) 101 107 111 113 123 129 131 137 > primes(50,140) 
schoolmath
In connection with the Le Monde puzzle of last week, I was looking for an R function that would give me the prime factor decomposition of any integer. Such a function exists within the package schoolmath, developped by Joerg Schlarmann and Josef Wienand. It is called prime.factor and it returns the prime factors of any 
Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).
