Question

How do I define a good pseudo-random number generator?

Answer 1

should be uniform distribution.

Answer 2

Interesting, I could define a good random number generator, but what can be good about a pseudo-random number generator?

Answer 3

I need one to complete my shuffling algorithm (the native pseudo_random number generator provided by my C implementation is deficient)

Answer 4

Couldnt you try to do something with time() ?

Answer 5

Here are 10000 random numbers for ya: http://www.agner.org/random/10000ran.zip

Answer 6

Maybe I could easily fix it; the problem is that the number it yields are too small (between 0 and 32767) :(

Answer 7

ah, what range are you looking for?

Answer 8

I need 50 million random numbers

Answer 9

All pseudo-random generators have a period, which is why it needs to be 'seeded' with something like time(). Look at this list. http://en.wikipedia.org/wiki/List_of_pseudorandom_number_generators

Answer 10

Would be great if it has an arbitrary range

Answer 11

Do you need your numbers to range from 0 to 50mil or do you want a series of 50m numbers?

Answer 12

range from 0 to 2^32 - 1

Answer 13

you could use the modulus operator to get them in a specific range

Answer 14

I doubt that after 50 million times, you're still going to have a 'uniform' distribution. More like a 'normal' distribution, but hey you're shuffling cards?

Answer 15

I want to shuffle huge lists of data.

Answer 16

In an array?

Answer 17

Maybe your problem will be memory?

Answer 18

nah my problem is the default RNG is too tiny - has a range of 0 to 32767

Answer 19

http://www.azillionmonkeys.com/qed/random.html

Answer 20

random * random * random * random would dramitically increase the range ;)

Answer 21

easy fix! thanks

Answer 22

Don't think that will work too well, for instance the lowest number you'll get after 32767 is 32767*2, assuming integers

Answer 23

check the distribution before you use it, i'm not sure it's completely usable...

Answer 24

I believe there is also another library function called random() instead of rand() that returns "long" values

Answer 25

yeah I think C++ has better random() functions.... one more reason for me to switch to C++