Version 1/080522 of Randomness by Mikael Segercrantz begins here.
"Random number generation using a simple seedable pseudorandom number generator."
Section 1 - The pseudorandom number generator kind
A pseudorandom number generator is a kind.
A pseudorandom number generator has a number called previous value.
A pseudorandom number generator has a number called multiplier.
A pseudorandom number generator has a number called adder.
Section 2 - Seeding the generator
To seed the random number generator (prng - a pseudorandom number generator) with (n - a number):
change the previous value of prng to n.
To set the multiplier of (prng - a pseudorandom number generator) to (n - a number):
change the multiplier of prng to n.
To set the adder of (prng - a pseudorandom number generator) to (n - a number):
change the adder of prng to n.
Section 3 - Initialize the generators
To initialize the random number generators:
let seed be 1234;
repeat with prng running through pseudorandom number generators:
change the multiplier of prng to 13;
change the adder of prng to 4399;
seed the random number generator prng with seed;
change the seed to seed + 1234.
When play begins:
initialize the random number generators.
Section 4 - Getting a random number
To decide what number is the next random number of (prng - a pseudorandom number generator):
let current value be the previous value of prng;
let current value be current value * multiplier of prng;
let current value be current value + adder of prng;
change previous value of prng to current value;
decide on current value.
To decide what number is the previous random number of (prng - a pseudorandom number generator):
decide on previous value of prng.
To decide what number is the next random number:
decide on the next random number of the main pseudorandom number generator.
To decide what number is the previous random number:
decide on the previous random number of the main pseudorandom number generator.
Section 5 - The main pseudorandom number generator
The main pseudorandom number generator is a pseudorandom number generator.
Randomness ends here.
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Chapter: Information on the Pseudorandom number generator
The Randomness extension creates a pseudorandom number generator kind, which has a few properties in it:
the previous value - the latest calculated random number
the multiplier - the multiplier used to create random numbers
the adder - the adder used to create random numbers
The pseudorandom number generator of the Randomness extension is of the most basic kind, utilizing the formula SEED = (SEED * MULT) + ADD to generate random numbers.
Chapter: The main pseudorandom number generator
This extension automatically creates one pseudorandom number generator called the main pseudorandom number generator. If your project requires multiple generators, you are free to create more of them, e.g. with
The skeleton in the closet pseudorandom number generator is a pseudorandom number generator.
Chapter: Seeding the PRNG
To seed the pseudorandom number generator created by the Randomness extension, you can use the following phrases:
seed the random number generator (name of generator) with (the seed value).
set the multiplier of (name of generator) to (the multiplier value).
set the adder of (name of generator) to (the adder value).
It is highly recommended that the multiplier be a prime number; the same can be said of the adder, although the extension does not require this.
Chapter: Reading values from the PRNG
You can read any pseudorandom number generator using the following syntax:
the next random number of (name of generator)
However, accessing the main pseudorandom number generator is somewhat easier:
the next random number
is enough to access it.
If you wish to read the last random number generated, you can use
the previous random number of (name of generator)
and
the previous random number
to access them.