ndhash

ndhash
==========
Javascript library to hash integer inputs into random-looking output.

This is a fast, simple (non-crypto) deterministic JS hash function that takes one
or more integer inputs and returns a float in the range 0..1 (like Math.random).
Its purpose is to produce output which (A) is reasonably well-distributed and
(B) doesn't show any obvious patterns when graphed over the inputs.

(It has not been tested for any other characteristics desirable to hash functions.)

$3

Here.

$3

// install with: npm install ndhash

var hash = require('ndhash')

hash(5) // 0.8459388134141277
hash(0,5) // 0.176296778517182
hash(5)==hash(5) // true

$3

(i.e. "why are you writing a hash function instead of using one made by
people smarter than you?")

I wanted a way to deterministically popluate a map (e.g. with trees),
without any obvious visual patterns in the result.
All of the existing hash functions I tried (e.g. FNV) seemed to produce
obvious patterns when graphing the output of hash(x,y) over (x,y).

$3

The algorithm is based on the one described
here
as the "Multiplication Method", attributed to Cormen, Leiserson, & Rivest (1990).
This version additionally offsets the inputs (so 0 doesn't clobber the output)
and repeats the process on each input, and then finally on a value
accumulated from all inputs. There is no theory underlying this;
it just seems to work (and seems not to work if I omit any steps).

$3

MIT. Improvements/suggestions most welcome.