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Re: RANDOMU bug (and HTML help)
Bill Thompson wrote:
> 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.
At first, I didn't understand what you were saying here - what could you
mean by "I don't get any random numbers at all"? Was it the same number
over and over again, or what? (In retrospect, I see that this is an
incorrect interpretation of the sentence..) Then I tried it myself:
IDL> delvar,seed & print,randomu(seed,3)
- and *no* output (hence "no random numbers at all")!
Seems like the guy who wrote the DELVAR command did something quite
IDL> delvar,seed & print,"HI"
- *still* no output!
Luckily, DELVAR cannot be used in programs!