good seeding for math.random

[osgeld]

Could you simplify this problem instance as much as possible and provide a demo? Are you sure that it is not due to some granularity of the velocities?

not that i am doubting anyone i tend to think the same

and no im not saying random is random, as far as i understand it there is no real random in computers, hince why 99% of the time you will see psudo rng listed, if nothing else to avoid debate, SO if you see constant patterns in your random numbers then i would assume something needs to be done to vary the humon perception of it

[invisisci]

This works 100% for me:

Code: Select all

function load()
  math.randomseed(os.time())
end

function update(dt) 
  local x = math.random(0, 500) --x will be a random integer 0-500 each run
end

[Tabasco]

I briefly re-visited my old starfield thing yesterday and noticed that I apparently already fixed it and forgot about it. I use math.random all over the place so I'm not sure what I was thinking the other night. Apparently very little.

[nunix]

I'm working with the OP on some of this stuff.

Code: Select all

function load()
   math.randomseed(os.time())
   font = love.graphics.newFont(love.default_font, 12)
   love.graphics.setFont(font)
   message = math.random(1,9)
end

function draw()
   love.graphics.draw(message, 100, 100)
end

This returns 8 every time. Why?!

[osgeld]

when i run it i get all sorts of results

(printing to command prompt (linux))

Code: Select all

6
4
7
7
8
6
1
4
6
5
7
4
4
1
4
7
7
9
6
8
2
3
8
8
7
4
5
7
6
1
3
3
4
9
9
2
6
1
6
3
6
4
7
9
4
1
7
2
1
3
9
3
5
8
1
3
2
5
1
8
5
3
1
9
2
1
2
8
1
7
1
7
1
7
7
4
8
4
6
9
7
6
2
3
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2
5
6
7
6
4
2
8
4
2
1
4
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8
5
9
9
3
1
7
9
5
6
4
1
5
1
6
6
4
9
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9
5
4
5
9
6
3
4
7
3
7
9
2
3
9
2
5
9
8
5
4
4
8
5
8
9
1
4
4
1
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3
6
5
7
5
2
1
8
8
4
6
8
5
9
7
6
5
7
4
9
QUIT love.system [Generic]

[philnelson]

I am wondering if this is possibly an OS X issue? Both nunix and I are running Mac OS X 10.5 intel.

[osgeld]

might be

[philnelson]

I get the same result: 8, every single time running it via the Love executable in OS X and Windows XP. On OS X I just double click test.love, on windows I click and drag test.love (which contains the main.lua file posted by nunix) onto the Love.exe. 8 every time.

[Tabasco]

Code: Select all

function load()
   math.randomseed(os.time())
   font = love.graphics.newFont(love.default_font, 12)
   love.graphics.setFont(font)
   message1 = math.random(1,9)
   message2 = math.random(1,9)
   message3 = math.random(1,9)

end

function draw()
   love.graphics.draw(message1 .. "--" .. message2 .. "--" .. message3, 100, 100)
end

message1 is always 9 for me (Windows XP, haven't tried on linux yet), but message2 and message 3 are random.
No matter how many times I load it, the first number returned is always 9 for me.

If I increase the range on message1 to 1-500, it will be 10 for a minute, then 11, then 12, then 13, but ONLY on the first request. Everything after that seems fine.
After composing this I ran it again and it's up to 20, then 21.

There's a little bit written about it under the math.random(seed) section here:
http://lua-users.org/wiki/MathLibraryTutorial

[philnelson]

The Wiki helped, specifically this:

Code: Select all

-- Initialize the pseudo random number generator
math.randomseed( os.time() )
math.random(); math.random(); math.random()
-- done. :-)

Calling math.random() 3 or 4 times before I actually need it seems to give me the results I need. Very weird.