R: Primes, Prime Factorization, Common Divisor

primefactors {spatstat.utils} | R Documentation

## Primes, Prime Factorization, Common Divisor

### Description

These functions find prime numbers, factorise a composite number into its prime factors, determine whether a number is prime, and find the least common multiple or greatest common divisor of two numbers.

### Usage

    primefactors(n, method=c("C", "interpreted"))
    divisors(n)
    is.prime(n)
    relatively.prime(n, m)
    least.common.multiple(n,m)
    greatest.common.divisor(n,m)
    primesbelow(nmax)

### Arguments

`n,m` | Integers to be factorized.
`nmax` | Integer. Upper limit on prime numbers to be found.
`method` | Character string indicating the choice of algorithm. (Developer use only.)

### Details

`is.prime(n)` returns `TRUE` if `n` is a prime number, and `FALSE` otherwise.

`primefactors(n)` factorises the integer `n` into its prime number factors, and returns an integer vector containing these factors. Some factors may be repeated.

`divisors(n)` finds all the integers which divide the integer `n`, and returns them as a sorted vector of integers (beginning with `1` and ending with `n`).

`relatively.prime(n, m)` returns `TRUE` if the integers `n` and `m` are relatively prime, that is, if they have no common factors.

`least.common.multiple` and `greatest.common.divisor` return the least common multiple or greatest common divisor of two integers `n` and `m`.

`primesbelow(nmax)` returns an integer vector containing all the prime numbers less than or equal to `nmax`.

### Value

`is.prime` and `relatively.prime` return a logical value.

`least.common.multiple` and `greatest.common.divisor` return a single integer.

`primefactors` and `primesbelow` return an integer vector.

### Author(s)

Adrian Baddeley Adrian.Baddeley@curtin.edu.au.

### Examples

      is.prime(17)

      relatively.prime(2, 3)

      primefactors(24) ## Note repeated factors

      divisors(24)

      greatest.common.divisor(60, 100)

      primesbelow(20)

[Package spatstat.utils version 1.13-0 Index]