Getting a random number wihout RND.

[Dav]

A while back I found some TI-84 code for a random number generator.  Played with it for a while, adapting it to QB64.  Messed with the calcs.  Gave it more randomness (I think) by feeding it the starting x/y position of the QB84 windows that seems to be placed randomly, and threw in TIMER for good luck.  I don't really understand it, but here it is for anyone interested in such a function.

- Dav

Code: (Select All)

'========

'RAND.BAS

'========

'Get a random number, without using RND

'Adapted for QB64 from TI-84 source found online.

'Thrown together By Dav, SEP/2023



'Since the QB64 window x/y position always starts at a

'random position, I'm using that as the seed starter.



_Delay .25



DIM SHARED seed: seed = _SCREENX * _SCREENY * TIMER



SCREEN _NEWIMAGE(800, 600, 32)



'Blocks of random size of random colors at random positions.



DO

    x = Rand(_WIDTH)

    y = Rand(_HEIGHT)

    s = Rand(100)

    r = Rand(255): g = Rand(255): b = Rand(255)

    LINE (x, y)-STEP(s, s), _RGB(r, g, b), BF

    _LIMIT 1000

LOOP





FUNCTION Rand (num)

    DIM z AS _INTEGER64, k AS _INTEGER64

    seed2 = seed * TIMER

    k = seed / 53668

    seed = 40014 * (seed - k * 53668) - k * 12211

    IF seed < 0 THEN seed = seed + 2147483563

    k = seed2 / 52774

    seed2 = 40692 * (seed2 - k * 52774) - k * 3791

    IF seed2 < 0 THEN seed2 = seed2 + 2147483563

    z = seed - seed2

    IF z < 1 THEN z = z + 2147483563

    Rand = z * 4.656613E-10 * 190000000 MOD num

END FUNCTION

[Dav]

Hmm, this works in older QB64 but I just tried it in QB84-PE and it's not working.  I should of tested it in that before posting .  Hang on and let me see if I can get it working in QB64-PE.

EDIT: Now it's working, had to add a _DELAY .25 at the beginning so _SCREENX/_SCREENY would be there.

- Dav

[bplus]

Hmm, this works in older QB64 but I just tried it in QB84-PE and it's not working.  I should of tested it in that before posting .  Hang on and let me see if I can get it working in QB64-PE.

EDIT: Now it's working, had to add a _DELAY .25 at the beginning so _SCREENX/_SCREENY would be there.

- Dav

Your seed sucks (dont take it personal), just set it to Timer.

No delay needed.

[Dav]

Hmm, this works in older QB64 but I just tried it in QB84-PE and it's not working.  I should of tested it in that before posting .  Hang on and let me see if I can get it working in QB64-PE.

EDIT: Now it's working, had to add a _DELAY .25 at the beginning so _SCREENX/_SCREENY would be there.

- Dav

Your seed sucks (dont take it personal), just set it to Timer.

No delay needed.

Gosh - I could had sworn when I tried it that way I was getting patterns (I tested with PSET).  But, it does seems to be working with just timer.

EDIT: Oh I bet that was when I was putting seed=timer inside the function at first, which didn't work well.

- Dav

[bplus]

Hmm, this works in older QB64 but I just tried it in QB84-PE and it's not working.  I should of tested it in that before posting .  Hang on and let me see if I can get it working in QB64-PE.

EDIT: Now it's working, had to add a _DELAY .25 at the beginning so _SCREENX/_SCREENY would be there.

- Dav

Your seed sucks (dont take it personal), just set it to Timer.

No delay needed.

Gosh - I could had sworn when I tried it that way I was getting patterns (I tested with PSET).  But, it does seems to be working with just timer.

EDIT: Oh I bet that was when I was putting seed=timer inside the function at first, which didn't work well.

- Dav

Or maybe it has to be past a certain time for timer to work? I just got lucky (i'm due).

[SMcNeill]

http://qb64phoenix.com/forum/showthread.php?tid=173 -- Might be interested in this old read as well.

[TerryRitchie]

I actually gave this some serious thought about 15 years ago and was going to build a proof of concept around an Arduino build.

Tune a receiver to 1.42 MHz (the hydrogen band) and sample the incoming signal 64 times. Above a certain noise threshold becomes a 1, at or below becomes a 0, then normalize the result to between 0 and .9999 repeating.

I envisioned Wifi chips could have the included 1.42 MHz receiver or a simple receiver circuit built into every motherboard for software to access to get true random numbers.

Never built it. Maybe I should dust this project off.

[Dav]

http://qb64phoenix.com/forum/showthread.php?tid=173 -- Might be interested in this old read as well.

Interesting.  Thanks for the link.

- Dav

[eoredson]

I would just set seed = timer
and run

Code: (Select All)

Do
    r = Rand(100)
    Print r;
    x = x + 1
    If x = 10 Then Exit Do
Loop

which seems to be quite accurate.

[euklides]

randomize timer ???