# prime_tools [![Crate](https://img.shields.io/crates/v/prime_tools.svg)](https://crates.io/crates/prime_tools) [![Build Status](https://travis-ci.org/danmedani/prime_tools.svg?branch=master)](https://travis-ci.org/danmedani/prime_tools)
This util provides a few tools for working with prime numbers.

Mostly for personal use with project euler problems. :)


```Rust
fn get_primes_less_than_x(x: u32) -> Vec<u32>
```
>Generates an ordered list of prime numbers from 2 up to x (exclusive).
>
>Uses the sieve of Eratosthenes under the covers.



```Rust
fn get_prime_factors_with_counts(x: u32, primes: &Vec<u32>) -> HashMap<u32, u32>
```
>To be used in conjunction with get_primes_less_than_x.
>Be sure to pass in `primes` at least up to sqrt(x).



```Rust
fn is_u32_prime(x: u32) -> bool
```
>Figures out if x is prime.
>This is fast! I've benchmarked it at 2.7 seconds to process 1 million random `u32`s.



```Rust
fn is_u64_prime(x: u64) -> bool
```
>Figures out if x is prime.
>This is pretty slow: I've benchmarked it at 26 seconds to process only 200 random `u64`s. :(



```Rust
fn get_primes_between(min: u64, max: u64) -> Vec<u64>
```
>Generates primes between min (inclusive) and max (exclusive). Uses a modified sieve of eratosthenes.
>
>WARNING #1: This can be very slow if the max is greater than 10^17 ish, or with too large a range.
>
>WARNING #2: This will break if the max is too much higher than 10^19 ish