gmp (version 0.2-2)

isprime: Determine if number is prime

Description

Determine whether the number is prime or not. 2: number is prime, 1, number is probably prime (without beeing certain), 0 number is composite.

Usage

isprime(n, reps = 40)

Arguments

n

Integer number, to be tested

reps

Integer, number of repeats

Value

• 0
  Number is not prime
• 1
  Number is probably prime
• 2
  Number is prime

Details

This function does some trial divisions, then some Miller-Rabin probabilisticprimary tests. reps controls how many such tests are done, 5 to 10 is a resonable number. More will reduce the chances of a composite being returned as "probably prime".

References

Gnu MP Library see http://swox.com/gmp, Home page: http://mulcyber.toulouse.inra.fr/projects/gmp/

[object Object]

nextprime isprime(210) isprime(71)

# All primes numbers from 1 to 100 t <-isprime(1:100) (1:100)[t>0] arith