Boost C++ Libraries: Ticket #7951: ranlux24_base(0) should be equal to ranlux24_base()

description changed

Marshall Clow — Wed, 30 Jan 2013 03:12:07 GMT

description modified (diff)

Fixed the formatting in the description.

Also, I verified the same behavior occurs with clang/libc++

Marshall Clow — Wed, 30 Jan 2013 04:31:08 GMT

The following change causes your test program to run successfully, and doesn't break any of the existing Boost.Random tests.

However, someone who understands the random code should probably review this and make sure it is the correct change.

Index: boost/random/subtract_with_carry.hpp
===================================================================
--- boost/random/subtract_with_carry.hpp	(revision 82663)
+++ boost/random/subtract_with_carry.hpp	(working copy)
@@ -161,7 +161,7 @@
                                         IntType, value)
     {
         typedef linear_congruential_engine<uint32_t,40014,0,2147483563> gen_t;
-        gen_t intgen(static_cast<boost::uint32_t>(value));
+        gen_t intgen(static_cast<boost::uint32_t>(value == 0 ? default_seed : value));
         detail::generator_seed_seq<gen_t> gen(intgen);
         seed(gen);
     }

Steven Watanabe — Wed, 30 Jan 2013 04:47:10 GMT

This fix appears to be correct, however,

a) Please fix subtract_with_carry_01_engine also. b) Please add a test case.

Marshall Clow — Wed, 30 Jan 2013 06:42:40 GMT

(In [82664]) Fix behavior with zero seed re: '26.5.3.3 [rand.eng.sub]/7'; thanks to stl@microsoft for the report; Refs #7951

milestone changed

Marshall Clow — Wed, 30 Jan 2013 06:43:10 GMT

milestone To Be Determined → Boost 1.54.0

owner, status changed

Marshall Clow — Sun, 10 Feb 2013 18:45:02 GMT

owner changed from No-Maintainer to Marshall Clow
status new → assigned

status changed; resolution set

Marshall Clow — Mon, 11 Feb 2013 16:19:12 GMT

status assigned → closed
resolution → fixed

(In [82820]) Merge Fix for zero seed in Boost.Random; Fixes #7951