[Numpy-discussion] random number generation in python compared to gsl

Giovanni Samaey giovanni.samaey@cs.kuleuven...
Thu Nov 6 13:25:58 CST 2008


Dear Robert,

indeed, this is the difference !  Thanks !  Seeding numpy with 4357  
gives identical sequences...

Giovanni


On 05 Nov 2008, at 19:01, Robert Kern wrote:

> On Wed, Nov 5, 2008 at 08:05, Giovanni Samaey
> <giovanni.samaey@cs.kuleuven.be> wrote:
>>>
>>> Hi,
>>> how about other seed values ?  I thought seed=0, is (often) used to
>>> mean a "random", i.e. current time or alike, seed value ... !?
>>
>> Not in this case: I always get the same sequence with seed=0
>> (different for both implementation, but the same each time I run it.)
>> I got around it by installing pygsl and taking random numbers from
>> there instead of from numpy.
>>
>> But I still find it strange to get two different sequences from two
>> implementation that claim to be the same algorithm...
>
> GSL has this bit of code:
>
>  if (s == 0)
>    s = 4357;   /* the default seed is 4357 */
>
> We don't. Otherwise, I believe the two seeding algorithms are  
> identical.
>
> -- 
> Robert Kern
>
> "I have come to believe that the whole world is an enigma, a harmless
> enigma that is made terrible by our own mad attempt to interpret it as
> though it had an underlying truth."
>  -- Umberto Eco
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