CODEWITHSUNDEEP
rfactorial
Junior Medrano
Junior Medrano

Reputation: 11

How can I calculate large numbers in this operation in RStudio?

I am executing this operation and when the process gives me NaN,

    Choques<-c(1:10)
    print (Choques)
    pr<-0
    n<-3818
    p<-0.040633627

    for(i in Choques) {
    pr[i]<-(factorial(n)/(factorial(Choques[i])*factorial(n-Choques[i])))*p^Choques[i]*(1-p)^(n-Choques[i]) 
    print (pr[i])
    }

However changing the value of the variable n for a smaller number let's say 20, if it shows numbers, I would like to know if there is any method to change the NaN by numbers, I suppose the numbers are too big.

Upvotes: 1

Views: 122

Answers (2)

John Coleman
John Coleman

Reputation: 52008

You are computing binomial probabilities in a loop and accumulating them in a vector. You can drop the factorials and even the loop by just using the vectorized function dbinom. Your loop can be replaced by the single line:

pr <- dbinom(Choques,n,p)

Upvotes: 1

St&#233;phane Laurent
St&#233;phane Laurent

Reputation: 84719

Replace

factorial(n)/(factorial(Choques[i])*factorial(n-Choques[i]))

with

choose(n, Choques[i])

Upvotes: 2

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