Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!sun-barr!olivea!uunet!ogicse!emory!hubcap!Steven
From: zenith@ensmp.fr (Steven Ericsson Zenith)
Newsgroups: comp.parallel
Subject: Example - Errata errata... opps.
Message-ID: <12909@hubcap.clemson.edu>
Date: 4 Feb 91 18:47:39 GMT
Sender: fpst@hubcap.clemson.edu
Lines: 44
Approved: parallel@hubcap.clemson.edu

Ah. Blush :-) This really will teach me to crow. Nick Carriero has
kindly pointed out my deficient knowledge of C. It turns out that the
program example I claimed deadlocks in it's Linda version - doesn't. My
sincere apologies Nick and Dave.

Nick says:

   First: Consider line 07. For 'me' in {2,3} limit is.
   (In C, assignment of a float to an int truncates the fractional part.)

   Second: Look at the for loop 09.  For 'me' in {2,3}, the conditional
   fails, we skip the loop, returning 1.  The tuples

	   ("prime table", 2, 1)
	   ("prime table", 3, 1)

   result.  These will allow further is_prime() evals to execute.

   01   is_prime(me)
   02        int        me;
   03   {
   04     int           i, limit, ok;
   05     double        sqrt();
   06   
   07     limit = sqrt((double) me) + 1;
   08   
   09     for (i = 2; i < limit; ++i) {
   10       rd("primes", i, ? ok);
   11       if (ok && (me%i == 0)) return 0;
   12     }
   13     return 1;
   14   }


   The bounds error is there---it in fact results from an editing error.

Steven
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