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Re: RANDOMU bug [message #14398 is a reply to message #14330]

Wed, 24 February 1999 00:00

Ivan Zimine
Messages: 40
Registered: February 1999

Member

William Thompson wrote:

> Here's another weird behavior of RANDOMU. If you call IDL with an undefined
> seed, it's supposed to initialize the seed for you. Thus, when you type in
>
> IDL> print,randomu(seed,3)
> 0.653919 0.0668422 0.722660
>
> before seed is defined to anything, it still works. Naively, I expected that
> if one deleted the seed variable, that would force IDL to re-initialize the
> seed, based on the system time or whatever. However, if my next command is
>
> IDL> delvar,seed & print,randomu(seed,3)
>
> I don't get any random numbers at all. To start getting random numbers again,
> I have to use a completely new variable name for the seed, e.g.
>
> IDL> print,randomu(seed2,3)
> 0.671149 0.383416 0.631635
>
> I don't know if this is properly speaking a bug or not, but it's certainly
> weird. As far as I can tell, this behavior is seen in all versions of IDL.
>
> Bill Thompson

On my Linux box i get exactely the same thing although I don't have to
use a new
variable for the seed.

IDL> print, !version
{ x86 linux unix 5.2 Oct 30 1998}
IDL> print,randomu(seed,3)
0.272710 0.897656 0.274907
IDL> delvar,seed & print,randomu(seed,3)
no output
IDL> print,randomu(seed,3)
0.00769819 0.365339 0.266145
this works too
IDL> delvar, seed
IDL> print,randomu(seed,3)
0.986642 0.277082 0.629543

Ivan Zimine

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[Message index]

		RANDOMU bug (and HTML help) By: landsman on Sun, 21 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: ajschmitt on Wed, 24 February 1999 00:00
		Re: RANDOMU bug By: Ivan Zimine on Wed, 24 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: steinhh on Wed, 24 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: thompson on Tue, 23 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: landsman on Tue, 23 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: landsman on Mon, 22 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: davidf on Mon, 22 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: ajschmitt on Mon, 22 February 1999 00:00
		Re: RANDOMU bug (and HTML help) By: mallors on Mon, 22 February 1999 00:00

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