[SciPy-user] random number
Gary Pajer
gpajer at rider.edu
Tue Jun 29 12:05:25 CDT 2004
Steve Schmerler wrote:
>>You're right. Wasn't seed changing but truly out of bound call.
>>Why do you need to generate uniform variate (0,1e38) ?
>>Curious about applications !
>>
>>JC.
>>
>>
>>
>
>I'm testing an evolution strategy (similar to a genetic algorithm) for
>parameter fitting. I need to construct parameter vectors
>
> p = [p[1], ..., p[n]]
>
>where each p[i] sould be a random number from 0 to 1e200.
>
>I found that the module 'random' works with the 1e39-thing.
>
> >>> from random import *
> >>> uniform(0,1e39)
> 2.3437216521520377e+038
> >>> uniform(0,1e200)
> 2.7167859425411156e+199
>
>But there is another downside here.
>
> >>> x=[uniform(0,1e200) for i in range(1000)]
>
>gives nearly 1000 rn's like
>
> 2.3107981948610023e+199
>
>All rn's have an order of magnitude of 1e199, but I want also things like
>e.g.
>
> 1e23, 1e45, 1e2, ....
>
>Any idea how to do this??? (google should do it :) )
>
>It seems as if 'uniform(min, max)' is implemented as
>
> random()*max
>
>where 'random()' is a random float out of [0,1).
>
>bye
>
>
>
I was going to suggest random()*1e39, but it seems that that is not
really what you want.
A uniformly distributed collection of numbers between (0, 1e38) is going
to have very few members between (0, 1e3). Or (0, 1e24). Or (0,
1e35). Only 1 in 10 will be in the range (0, 1e37). It sounds like
you may be looking for logarithmically distributed numbers.
How about 10**x where x is a random number in (0, 38).
Caveat: I'm no expert in random numbers. I'm just following my nose, here.
-gary
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