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From: "Lavrentiev, Anton (NIH/NLM/NCBI) [C]" <lavr@ncbi.nlm.nih.gov>
To: "newlib@sourceware.org" <newlib@sourceware.org>
Cc: Corinna Vinschen <vinschen@redhat.com>,
	"cygwin@cygwin.com" <cygwin@cygwin.com>
Subject: RE: [EXTERNAL] Re: rand is not ISO C compliant in Cygwin
Date: Mon, 13 Nov 2023 16:44:08 +0000	[thread overview]
Message-ID: <DM8PR09MB7095FD4287584FC53200831CA5B3A@DM8PR09MB7095.namprd09.prod.outlook.com> (raw)
In-Reply-To: <ZVJM7g9smHGMN7QH@calimero.vinschen.de>

IMHO:

>   2. A different sequence

The word "different" in this context is ambiguous: is it "unrelated" as a generator, or is it "not the same" sequence of the actual numbers?

> I read this as the newlib technique being one way of correctly implementing rand/srand, no?

If the first, then yes; but if the second, then no.

The problem with the first approach is, however, is the inability to adequately randomize your code (e.g. for testing).

You call srand() in the main() thread, and then spawn threads thinking they will inherit the randomization; but in fact, they all start off the same number sequence, regardless.

Anton Lavrentiev
Contractor NIH/NLM/NCBI


  reply	other threads:[~2023-11-13 16:44 UTC|newest]

Thread overview: 18+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-11-10 20:19 Bruno Haible
2023-11-10 21:39 ` Norton Allen
2023-11-10 22:27   ` Bruno Haible
2023-11-11 16:50     ` Allen, Norton T.
2023-11-11 18:25       ` René Berber
2023-11-11 20:18         ` Allen, Norton T.
2023-11-13 14:17 ` Corinna Vinschen
2023-11-13 14:25   ` Bruno Haible
2023-11-13 14:38     ` Corinna Vinschen
2023-11-13 16:21       ` Corinna Vinschen
2023-11-13 16:44         ` Lavrentiev, Anton (NIH/NLM/NCBI) [C] [this message]
2023-11-13 21:33         ` Bruno Haible
2023-11-13 22:14           ` Glenn Strauss
2023-11-14 10:20             ` Corinna Vinschen
2023-11-14 10:11           ` Corinna Vinschen
2023-11-14 11:52             ` Bruno Haible
2023-11-14 16:59               ` Corinna Vinschen
2023-11-14 18:06                 ` Bruno Haible

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