https://github.com/draeder/primeget
Generate prime numbers algorithmically
https://github.com/draeder/primeget
Last synced: about 1 month ago
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Generate prime numbers algorithmically
- Host: GitHub
- URL: https://github.com/draeder/primeget
- Owner: draeder
- License: mit
- Created: 2022-07-20T21:21:39.000Z (almost 3 years ago)
- Default Branch: master
- Last Pushed: 2022-07-28T11:16:21.000Z (almost 3 years ago)
- Last Synced: 2025-03-23T11:18:22.197Z (about 2 months ago)
- Language: JavaScript
- Homepage:
- Size: 32.2 KB
- Stars: 0
- Watchers: 1
- Forks: 0
- Open Issues: 0
-
Metadata Files:
- Readme: README.md
- License: LICENSE
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README
# Primeget (WIP)
## Generates prime numbers algorithmically
Primeget is a prime number generator combined with a prime checking method to discard non-primes. It is capable of generating primes from a given range.
Generating the primes in `n = 9_000_000_000_000_000` to `z = 9_000_000_000_001_000` takes approximately ~29s.
A range between `n` and `n + 1000` seems to be the sweet spot without crashing V8.
## Usage
```js
import primeget from 'primeget'
let primes = primeget(0, 10) // [ 2, 3, 5, 7, 11, 13, 17 ]
// Interesting things happen here. Anything above `n = 97` returns nothing, but `n <= 97` is notable.
primes = primeget(97, 0)
/*
[ 97 ]
*/
primes = primeget(10, 0)
let set = [...new Set(primes)].sort((a, b) => a - b)
/*
[
3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41,
43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97,
101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157,
163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227,
229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283,
293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367,
373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439,
443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509,
521, 523, 541, 547,
... 229 more items
]
*/
```
### Example
```js
import Primeget from 'primeget'
let n = 9_006_999_999_998_000
let z = 9_006_999_999_999_000
console.time('Time')
let primes = primeget(n, z)
console.timeEnd('Time') // About 10 seconds
// remove duplicates and sort
primes = [...new Set(primes)].sort((a, b) => a - b)
console.log(primes)
console.log('Last:', primes.slice(-1)[0])
console.log('Total:', primes.length)
```
## API
My goal was to create a simple API for this sheep counting prime number generator. It should be quite flexible. The CLI I built is an example of how it can be extended. Submit an [issue](https://github.com/draeder/Primeget/issues) if it doesn't meet your needs.
### API Usage
```js
import Primeget from '../api.js'
import { check } from '../primeget.js'
let primeget = new Primeget()
let isPrime = check(101) // true
```
### `check(n)`
Check if `n` is prime
Returns `true` if prime, `false` if not prime
### `primeget.make(n, z)`
Generate a set of prime numbers starting wih `n` until `z`.
This is an O(n) function and may crash things if the range is too great. **I am not a mathematician, so O(n) may be wrong; please correct me!**
### `primeget.get()`
Return a sorted and filtered array of primes generated by `primeget.make(n, z)`
### `primeget.raw()`
Return the raw numbers calculated by Primeget before sorting and filtering
### `primeget.length`
Return the length of the sorted and filtered array of primes generated by `primeget.make(n, z)`
## CLI
A simple CLi with some basic features.
### CLI install
```
npm i primeget -g
```
### CLI Usage
```js
> primeget // initiates Primeget cli
// generate some primes
primeget > make 0 100
// print the array of primes
primeget > get
// print the length of array of primes
primeget > get -l
// print prime at the provided index
primeget > get 187
// print a random element from the array of primes
primeget > get -r
// print array of primes between 30 and 40
primeget > get 30 40
// print array of primes between 30 and 40
// along with length of the array of primes between 30 and 40
primeget > get 30 40 -l
// another way to print the length of the current set of primes
primeget > length
// print if a number is prime (not depedant on the Primeget generated primess)
primeget > check 111 // false
// quit Primeget
primeget > 'quit' or 'exit' or 'bye' or 'close' or 'end' or 'ctrl+c'
```
## About
> I'm not a mathemetician. But I can count sheep.
Nearly 20 years ago, I had a bout of insomnia. Instead of counting sheep that night, I calculated prime numbers starting with `0 + 1 != prime`, then `1 + 1 = prime`, then `1 + 2 = prime`, and so-on, along with some subtraction between the previous two primes. I realized the system I devised worked with larger numbers, too.
I didn't know how to program very well at the time, so my attempt to test the pseudocode I wrote down was a failure. For the record, I slept very little that night.
I have since lost that pseudocode and forgot the details, but suddenly recalled parts of the methodology. Using pieces of that recollection plus a prime check and passing in previous primes, I have been successful at generating primes with this code.
## Contribution
If you are a mathematician, it would be great to have your feedback and/or PR on this algorithm!
## License
MIT