https://github.com/JeffersonLab/drand48

Nim implementation of standard unix drand48 random number generator
https://github.com/JeffersonLab/drand48

Last synced: about 2 months ago
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Nim implementation of standard unix drand48 random number generator

• Host: GitHub
• URL: https://github.com/JeffersonLab/drand48
• Owner: JeffersonLab
• License: bsd-3-clause
• Created: 2017-09-29T16:22:23.000Z (almost 7 years ago)
• Default Branch: master
• Last Pushed: 2020-12-22T22:06:56.000Z (over 3 years ago)
• Last Synced: 2024-05-18T14:33:39.839Z (4 months ago)
• Language: Nim
• Size: 15.6 KB
• Stars: 0
• Watchers: 6
• Forks: 0
• Open Issues: 1
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

Awesome Lists containing this project

• awesome-nim - drand48 - Nim implementation of the standard Unix drand48 random number generator. (Operating System / Randomization)

README

        
# Drand48 [![Build Status](https://travis-ci.org/JeffersonLab/drand48.svg?branch=master)](https://travis-ci.org/JeffersonLab/drand48)

Nim implementation of the standard unix drand48 pseudo random number generator.

All the routines work by generating a sequence of 48-bit integer values, Xi , 

according to the linear congruential formula:

Xn+1 = (aXn + c) mod m   n>= 0

The parameter m = 248; hence 48-bit integer arithmetic is performed. 

The multiplier value a and the addend value c are given by:

a = 0x5DEECE66D = 0c273673163155

c = 0xB = oc13

The value returned by any of the drand48() is computed by first

generating the next 48-bit Xi in the sequence. Then the appropriate

number of bits, according to the type of data item to be returned, are

copied from the high-order (leftmost) bits of Xi and transformed into the returned value.

 

The drand48() function stores the last 48-bit Xi generated in an 

internal buffer; that is why they must be initialised prior to being invoked. 

The initializer function srand48() sets the high-order 32 bits of Xi to 

the low-order 32 bits contained in its argument. The low-order 16 bits 

of Xi are set to the arbitrary value 0x330E .

The initializer function seed48() sets the value of Xi to the 48-bit value 

specified in the argument array. The seed can be set with the 48-bit

seed split into four 12-bit chunks, or as a 48-bit int.

There are functions savern12() and savern48() that returns the current random number seed.