# primecount-rs

primecount-rs is a library that provides APIs for counting the primes below an integer x ≤ 10^31 
using highly optimized implementations of the combinatorial 
[prime counting algorithms](https://en.wikipedia.org/wiki/Prime-counting_function#Algorithms_for_evaluating_%CF%80(x)).

It is a rust wrapper around an awesome [kimwalisch/primecount](https://github.com/kimwalisch/primecount) library.

**References**:
- [crates.io/crates/primecount](https://crates.io/crates/primecount)
- [docs.rs/primecount](https://docs.rs/primecount)

## API

**Add to Cargo.toml of your project:**
```
primecount = "0.2.0"
```

**Examples:**
```rust
use primecount;

fn main() {
    println!("Primes below 1000 = {}", primecount::pi(1000));
    println!(
        "Numbers below 1000 that are not divisible by 
        any of the first 100 primes (a.k.a. Legendre-sum) = {}",
        primecount::phi(1000, 100)
    );
    println!("10th prime = {}", primecount::nth_prime(10));
}
```

## Contribute

1. Install [cmake](https://cmake.org/)
2. Update primecount dependency:
```
git submodule update --init --recursive
```
3. `cargo build` to build the library
4. `cargo test` to run the tests