[fpc-pascal] Re: random numbers negative

2011-08-17 Thread Lukasz Sokol
On 16/08/2011 16:25, Luis Fernando Del Aguila Mejía wrote: > I have a doubt. > With the random function, Can you generate random numbers negative? > > Begin > randomize; > Writeln (random (-127)) / / 0> = n> -127 > End. > > thanks. As only negative range : somebody (Felipe) wrote that: ( -1*Ran

Re: [fpc-pascal] Re: random numbers

2006-03-09 Thread Vinzent Hoefler
On Thursday 09 March 2006 17:47, Jonas Maebe wrote: > On 9 mrt 2006, at 18:38, Vincent Snijders wrote: > > > > Indeed, it isn't a real random number generator and in fact this is > > a good thing, otherwise you wouldn't be able to reproduce any > > behaviour with a Pseudo RNG. The fact it is Pseudo

Re: [fpc-pascal] Re: random numbers

2006-03-09 Thread Jonas Maebe
On 9 mrt 2006, at 18:38, Vincent Snijders wrote: As I noticed, when initialized the randseed with the same value, the whole rand values in the chain will be totally identical, which I'm afraid is rather far from what we might expect from a "real" random number generator! Indeed, it isn't

Re: [fpc-pascal] Re: random numbers

2006-03-09 Thread Vincent Snijders
Antal wrote: As I noticed, when initialized the randseed with the same value, the whole rand values in the chain will be totally identical, which I'm afraid is rather far from what we might expect from a "real" random number generator! Indeed, it isn't a real random number generator and in fa

[fpc-pascal] Re: random numbers

2006-03-09 Thread Antal
There is nothing strange about this. Randomize initialises randseed based on the system clock value expressed in seconds. So if you run it twice in the same second, you will get the same number. You are not generating a series of random numbers based on the Mersenne Twister here, because you only

Re: [fpc-pascal] Re: Random numbers

2006-03-06 Thread Alain Michaud
Hi, I am not a mathematician myself, but I predict that unless you make extensive tests over a very long period of time you will never find any corelations! On Mon, 2006-03-06 at 13:39 +0100, Jonas Maebe wrote: > On 6 mrt 2006, at 13:37, Antal wrote: > > >> The Mersenne Twister Free Pascal

Re: [fpc-pascal] Re: Random numbers

2006-03-06 Thread Vinzent Hoefler
On Monday 06 March 2006 12:37, Antal wrote: > > The Mersenne Twister Free Pascal uses is one of the best PRNGs > > known today, it just has to be used the right way. But calling it > > from several threads and "randomly" overwriting its state array is > > definitely not the right way to use it. >

Re: [fpc-pascal] Re: Random numbers

2006-03-06 Thread Jonas Maebe
On 6 mrt 2006, at 13:39, Jonas Maebe wrote: And then you have to compare the random numbers generated in one such a program run, not between different runs. And note that even then you may get two times the same number after each other. There is nothing wrong with that though, since if tha

Re: [fpc-pascal] Re: Random numbers

2006-03-06 Thread Jonas Maebe
On 6 mrt 2006, at 13:37, Antal wrote: The Mersenne Twister Free Pascal uses is one of the best PRNGs known today, it just has to be used the right way. But calling it from several threads and "randomly" overwriting its state array is definitely not the right way to use it. I'm disappointed, be

[fpc-pascal] Re: Random numbers

2006-03-06 Thread Antal
|Random numbers should not be generated with a method chosen at random. | -- Donald E. Knuth |The generation of random numbers is too important to be left to chance. |-- Robert R. Coveyou, Oak Ridge National Laboratory, 1969 The Mersenne Twister Free Pascal uses is one of the best