Scratch

I have seen this in other computer generated random engines and I think I know what the problem is. Inherantly a computer cannot make something random as all its components are based on fixed rules. Therefore when a programme operates a 'random function' it actually is basing it on a variable hidden inside the programming that somehow changes overtime but not in a random fashion. In this case I think, from what you are saying about it being similiar whenever you open scratch, that this variable may be to do with how long scratch has been open and this variable resets whenever the Scratch programme is opened so really it isn't random at all. I hope this has helped.

As noted in the earlier post, the usual "random" number generator is actually a pseudo-random number generator (PRNG) and starts with a seed number (often some system variable, the choice of which is probably the reason for different behavior for the local and web programs) to generate a sequence. 

The same seed, at least for the simpler algorithms, will always generate the same sequence.  (This is a great (!) benefit for application testing.)  Having the ability to manually enter your own seed would be a nice "feature" for Jan's program - you could reproduce a sequence you liked with one pass.

If you look up pseudorandom (no hyphen) numbers in Wiki, you will see an immense amount of information and many options to produce more randomness. If you want to generate your own sequence, any of the very simple algorithms shold work fine unless you are doing encryption or Monte Carlo simulations.  For more randomness, you could add or multiply your number and Scratch's number together and truncate as needed.  (Of course, if you want to use the "Blum Blum Sbub" or the "Mersenne Twister" - go right ahead.  )

(As an aside, trying two or three different PRNG algorithms and evaluating the results makes a good Middle School/High School level science fair project. I've seen two or three variations on this theme and the reaction from spectators (and in some cases, judges) was much like Jens' - "You mean the numbers from my computer aren't really random?")

So in english, no thanks to MartinWollenweber, it works like a claw grabber machine, over time it changes in value.

PS This random thing did make me think, how could a computer be random?

Dave911 wrote:

I have seen this in other computer generated random engines and I think I know what the problem is. Inherantly a computer cannot make something random as all its components are based on fixed rules. Therefore when a programme operates a 'random function' it actually is basing it on a variable hidden inside the programming that somehow changes overtime but not in a random fashion. In this case I think, from what you are saying about it being similiar whenever you open scratch, that this variable may be to do with how long scratch has been open and this variable resets whenever the Scratch programme is opened so really it isn't random at all. I hope this has helped.

it cood also be like if u hav 3 choses,there isn't much of anything to randomly pick from!!!

Truely it is not  random at all.

I think in a random 1 to 10 numbres the 4th to 7th numbres  are all 7.
So really how random it is, is how the people made scratch whitch is not random at all.


How do you spell whitch I think that is the wrong way?

In v1.2.1, I think that the random number generator does start differently each time, but I haven't checked to be sure.  In v1.0 I believe it was always seeded the with the same seed, so that each run was the same.

I've not done test son their pseudorandom number generator, but if they used any of the standard library ones, it requires some fairly sophisticated tests to detect that it is not random.

Scratch team, care to tell us which pseudorandom number generator you used?