# Fast Functions for Prime Numbers in R

Authors: Os Keyes and Paul Egeler
License: MIT

## Description

This R package has several utility functions for dealing with prime numbers, such as checking for primality and generating prime numbers. Additional functions include:

• finding prime factors and Ruth-Aaron pairs
• finding next and previous prime numbers in the series
• finding or estimating the nth prime
• estimating the number of primes less than or equal to an arbitrary number
• computing primorials
• finding prime k-tuples (e.g., twin primes)
• finding the greatest common divisor and smallest (least) common multiple
• testing whether two numbers are coprime
• computing Eulerâ€™s totient (phi)

The package also provides an R dataset containing the first one thousand primes.

## Installation

You can install the released version of primes from CRAN with:

``install.packages("primes")``

And the development version from GitHub with:

``````# install.packages("devtools")
devtools::install_github("ironholds/primes")``````

## Example

This checks which of the first twenty natural numbers are prime:

``````library(primes)

is_prime(1:20)
## [1] FALSE  TRUE  TRUE FALSE  TRUE FALSE  TRUE FALSE FALSE FALSE  TRUE FALSE  TRUE FALSE
## [15] FALSE FALSE  TRUE FALSE  TRUE FALSE``````

You can also generate all the prime numbers between 101 and 199 with the following:

``````generate_primes(101, 199)
## [1] 101 103 107 109 113 127 131 137 139 149 151 157 163 167 173 179 181 191 193 197 199``````