https://github.com/qqwy/elixir-sequences

Defines a module containing many common integer sequences (even numbers, odd numbers, primes, factorials, fibonacci, etc)
https://github.com/qqwy/elixir-sequences

Last synced: 7 months ago
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Defines a module containing many common integer sequences (even numbers, odd numbers, primes, factorials, fibonacci, etc)

• Host: GitHub
• URL: https://github.com/qqwy/elixir-sequences
• Owner: Qqwy
• License: mit
• Created: 2016-03-20T08:15:41.000Z (over 9 years ago)
• Default Branch: master
• Last Pushed: 2022-11-28T03:05:31.000Z (almost 3 years ago)
• Last Synced: 2025-02-27T11:35:50.586Z (7 months ago)
• Language: Elixir
• Size: 270 KB
• Stars: 22
• Watchers: 5
• Forks: 1
• Open Issues: 8
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

          

# Sequences

[![hex.pm version](https://img.shields.io/hexpm/v/sequences.svg)](https://hex.pm/packages/sequences)

[![Build Status](https://travis-ci.org/Qqwy/elixir-sequences.svg?branch=master)](https://travis-ci.org/Qqwy/elixir-sequences)

This Elixir Module defines many useful integer sequences.

These sequences are created as Streams, which means that they are lazily evaluated.

Most of these sequences use a recurrence relation that calculates the *n*-th element from *n-1* or other earlier known data. This means that if you only want the *n*-th item of a Sequence, there might be another algorithm that is faster; But if you want multiple consecutive elements of a Sequence, this module is right up your alley!

Repository: [https://github.com/Qqwy/elixir-sequences](https://github.com/Qqwy/elixir-sequences)

## List of included sequences:

- `Sequences.integers(start, step)`: a helper function to create any kind of lazy integer sequence with a regular step distance.

- `Sequences.integers`

- `Sequences.positive_integers` 

- `Sequences.odd_integers`

- `Sequences.even_integers` 

- `Sequences.zeroes`

- `Sequences.ones`

- `Sequences.factorials`

- `Sequences.fibonacci`

- `Sequences.catalan`

- `Sequences.triangular`

- `Sequences.primes`

- `Sequences.squareroot_tuple(n)`: Returns a tuple with an integer part (single integer number) and decimal part (digit stream)

- `Sequences.squareroot_tuple(n, num_of_digits)`: Returns a tuple with an integer part (single integer number) and decimal part (digit list with given length)

- `Sequences.squareroot_decimals(n)`: Returns decimal stream of the decimal expansion of a square root.

- `Sequences.squareroot_expansion/1`: Returns a digit stream of the decimal expansion of a square root, including the digits of the integral part at the front.

## A note on Prime numbers

There are multiple known ways to generate prime numbers. Because each of these variants might have a different *(time, memory)-efficiency* on different intervals, prime generation variants can be called directly:

- Sequences.Primes.trial_division

(For now, there is only this one)

`Sequences.primes` uses `Sequences.Primes.trial_division` internally. This might change in the future.

## Installation

This package is [available in Hex](https://hex.pm/packages/sequences)

  1. Add sequences to your list of dependencies in `mix.exs`:

        def deps do

          [{:sequences, "~> 1.1.0"}]

        end

  2. Ensure sequences is started before your application:

        def application do

          [applications: [:sequences]]

        end

## Changelog

- 1.1.1: Update dependency versions to newer ones. Drops support for Elixir < 1.3

- 1.1.0: Sequences for square root expansions.

- 1.0.0: First fully-functional version.