Re: RANDOMU bug (and HTML help)

[landsman(at)stars.gsfc.nasa.gov (Wayne Landsman)]

In article <7ascms$kin$1@nnrp1.dejanews.com>, ajschmitt@my-dejanews.com writes...
>This is not the worst of it. For some of us, it is important to be able
>to have the same seed so that the same "random" sequence is produced.
>However, RSI quietly changed the manner in which the SEED variable
>interacts with the RANDOM functions between version 5.0 & 5.1.
> 
>Consider the following behavior from IDL v 5..0.3:
>IDL> seed = 2 & print, randomu(seed, 3)
>     0.342299     0.402381     0.307838
>....doing this multiple times will always give the same result.
> 
>However, in IDL v.5..1 & later,. using this several times in a row
>produces different results each time.:
>IDL> seed = 2 & print, randomu(seed, 3)
>    0.0594004     0.982075     0.358593
>IDL> seed = 2 & print, randomu(seed, 3)
>     0.831999     0.303037     0.506712

What exact version and machine are you using?     On Solaris under IDL V5.2, 
RANDOMU works as described above for V5.0.3.    I suppose that those of us who
use the RANDOMU function will have explicitly watch for specific IDL versions
and machines (like we used to have to do for BYTEORDER).   Sigh...

IDL> print,!VERSION
{ sparc sunos unix 5.2 Oct 30 1998}
IDL> seed = 2 & print,randomu(seed,3)
     0.342299     0.402381     0.307838
IDL> seed = 2 & print,randomu(seed,3)
     0.342299     0.402381     0.307838    

--Wayne Landsman                                 landsman@mpb.gsfc.nasa.gov