From: "Nadav Har'El" <nyh@cloudius-systems.com>
To: musl@lists.openwall.com
Subject: Re: drand48() gives wrong sequence?
Date: Sun, 21 Sep 2014 15:20:25 +0300 [thread overview]
Message-ID: <CANEVyjvCd2VgrQckMs9q+uAeiT=J41y1RTDrEEBsbg2LNTp5TQ@mail.gmail.com> (raw)
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>Am Sonntag, den 21.09.2014, 14:45 +0300 schrieb Nadav Har'El:
>> Any ideas why I'm getting the wrong sequence?
>
>I don't think you are getting the wrong sequence, you are just
>printing it wrong. "%ld" is for long double and not for double.
>
>Jens
(I tried to subscribe to the mailing list but it didn't work, so please CC
me with further responses).
"%ld" is not a double at all, it's an int.
My message's title was indeed somewhat confusing, because I mentioned
drand48() in the title but used lrand48() in my example code. I saw the
same problem of a different sequence also with drand48() (printed with %g
of course) - but at the end decided to include code which printed lrand48().
Anyway, "%ld" is the right thing to use here because lrand48() returns a
"long int".
Replacing it with "%d" makes no difference and the sequences are still
different (I tried). This is because while lrand48()'s type is officially
"long", its return value is just 32-bit, so one can treat it just fine as
either long (64-bit on my 64-bit machine) or int (32-bit) and you get the
same result.
--
Nadav Har'El
nyh@cloudius-systems.com
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next reply other threads:[~2014-09-21 12:20 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-09-21 12:20 Nadav Har'El [this message]
2014-09-21 12:40 ` Jens Gustedt
-- strict thread matches above, loose matches on Subject: below --
2014-09-21 11:45 Nadav Har'El
2014-09-21 12:02 ` Jens Gustedt
[not found] ` <CANEVyjv9wwEBibFjqV7XTLzBU2BLvpVPzvxig7ArGceOfpzY7w-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2014-09-21 13:27 ` Justin Cormack
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