Prime-Checker

A sample rust package to check the prime-ness of a given unsigned, 64-bit integer.

Description

Do note that wherever we use square brackets in this section, we are using the mathematical expression for an inclusive boundary.

Any whole number (or natural number, depending on who you ask) num, can have one of the following three prime-ness values:

1. Prime: The list of its factors is exactly [1, num].
2. Composite: The list of its factors is [1, [z (- Z], num] where z can be any natural number exclusively between 1 and num.
3. Anti-Prime: The list of its factors is the same as a composite number (except in special cases, such as 1, 2) but the length of the list is the greatest for the set [num-z, num] i.e, it exclusively has the highest number of factors for any natural number less than it.

The library here holds functions that help determine and select unsigned, 64-bit integers depending on these three criteria.

Documentation

The autogenerated Rust documentation can be viewed at the Docs.RS website.

It may take a few hours for docs to propagate after a new version has been uploaded, you can check the build queue here.

Here we will go over the very basics of the functions defined in the lib.rs file.

1. is_hcn()

   • Checks if the given number is a highly-composite (anti-prime) number.

   • Arguments: num: u64

   • Returns: bool | default: false, Vec<u64> where the vector is list of the given number, num's factors.

   • Usage:

     use prime_checker;
     
     fn main(){
         let num: u64 = z; // z belongs to the set of natural numbers and is only used as a placeholder by us in this README.
         let check: bool;
         let factors: Vec<u64>;
     
         (check, factors) = prime_checker::is_hcn(num: num);
         if check == true{
             println!("{} is a highly composite number.", num);
         }
         else {
             println!("{} is not a highly composite number; here are its factors: {:?}", num, factors);
         }
     }
     

2. is_prime()

   • Checks if the given number is a prime number.

   • Arguments: num: u64

   • Returns: bool | default: false, Vec<u64> where the vector is list of the given number, num's factors.

   • Usage:

     use prime_checker;
     
     fn main(){
         let num: u64 = z; // z belongs to the set of natural numbers and is only used as a placeholder by us in this README.
         let check: bool;
         let factors: Vec<u64>;
     
         (check, factors) = prime_checker::is_prime(num: num);
         if check == true{
             println!("{} is a prime number.", num);
         }
         else {
             println!("{} is not a prime number; here are its factors: {:?}", num, factors);
         }
     }
     

3. description()

   • Returns a brief description of this library crate and if show is set to true, prints the same to the console.

   • Arguments: show: bool

   • Returns: String

   • Usage:

     use prime_checker;
     
     fn main(){
         let desc_str = prime_checker::description(true);
     }
     

4. get_primes()

   • Finds all prime numbers which are less than or equal to the given number.

   • Arguments: num: u64

   • Returns: Vec<u64> where the vector is list all prime numbers which are less than or equal to the given number, num.

   • Usage:

     use prime_checker;
     
     fn main(){
         let num: u64 = z; // z belongs to the set of natural numbers and is only used as a placeholder by us in this README.
         let prime_numbers: Vec<u64>;
     
         prime_numbers = prime_checker::get_primes(num: num);
         println!("The prime numbers till {} are:\t{:?}", num, prime_numbers);
     }
     

5. get_hcn()

   • Finds all anti-prime numbers which are less than or equal to the given number.

   • Arguments: num: u64

   • Returns: Vec<u64> which is the list of all highly-composite numbers less than or equal to the given number, num.

   • Usage:

     use prime_checker;
     
         fn main(){
             let num: u64 = z; // z belongs to the set of natural numbers and is only used as a placeholder by us in this README.
             let anti_prime_numbers: Vec<u64>;
     
             anti_prime_numbers = prime_checker::get_hcn(num: num);
             println!("The anti-prime numbers till {} are:\t{:?}", num, anti_prime_numbers);
         }
     

   • WARNING: HIGHLY Unoptimized and Computationally Expensive[^1].

Development and Contribution

If you want to contribute to this library, kindly follow the steps described below.

Contribution Workflow

1. Assign or ask a moderator to assign yourself to the required issue; this is to ensure that the same issue is not being independently resolved by two or more unrelated parties.
2. If not already done, fork the repository to your own github account.
3. If this is your first time contributing, follow the steps given in the following section to set up the development environment.
4. Checkout a branch named as an url-safe version of the issue number.
   • Suppose the issue number is Misc_001, then the branch name will be misc-001.
5. Make the code changes as required.
   • Also, write any additional test-cases required in the required module/file.
6. Run cargo test --verbose to make sure everything works and is validated.
   • Do NOT proceed further until all tests pass.
7. Commit your changes with a meaningful commit message.
8. Merge with the master branch of the main repository and run all tests again.
   • Do NOT proceed further until all tests pass.
9. Push to the origin.
10. Create a new Pull Request to the master branch of the main repository with the required details and a sensible PR title.
11. If review changes are requested, repeat steps #5-9 until no more changes are requested.

Development Environment Setup

Make sure the pre-requisites are satified before proceeding further.

DO NOT use the nightly build of Rust for this. We cannot vouch for any behaviour due to differences between the stable and nightly builds.

Pre-Requisites

1. Rust Compiler
   • v1.6+ (stable)
2. BASH
   • GitBash for Windows
3. Cargo

Steps

1. chmod +x scripts/* to give all scripts in the scripts directory permission to execute.

   • You really should go through the scripts before doing this; just good practice.

2. sh scripts/build.sh both to build both, the release and debug versions of the library.

3. cargo test --verbose to make sure everything was copied correctly and is working as intended.

Credits

(ɔ) 2023 Arkiralor (Prithoo Medhi)

[^1]: Takes approximately 64 seconds to check 6'160 values beyond the last element of prime_checker::libs::constants::KNOWN_ANTIPRIMES.