[Boost-bugs] [Boost C++ Libraries] #12625: multiprecision acos() sometimes does not return

Subject: [Boost-bugs] [Boost C++ Libraries] #12625: multiprecision acos() sometimes does not return
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2016-11-26 03:40:51

#12625: multiprecision acos() sometimes does not return
------------------------------+----------------------------
 Reporter:  steve@…           |      Owner:  johnmaddock
     Type:  Bugs              |     Status:  new
Milestone:  To Be Determined  |  Component:  multiprecision
  Version:  Boost 1.62.0      |   Severity:  Problem
 Keywords:                    |
------------------------------+----------------------------
 Thibaut Paumard reported the following bug to Debian as
 https://bugs.debian.org/844495


 Some inputs cause multiprecision acos() to hang.  The following example
 hangs on s390x:

 {{{
 #include <boost/multiprecision/cpp_dec_float.hpp>

 int main(int argc, char** argv) {

   boost::multiprecision::cpp_dec_float_100 alpha100, a, b;
   alpha100=5.9839860068377014046259e-02;
   b=cos(alpha100);
   a=acos(b);

   return 0;
 }
 }}}


 Known affected architectures include arm64 armel armhf mips64el mipsel
 ppc64el s390x powerpc ppc64.  It's not clear to me whether the value of
 alpha100 needs to be adjusted to trigger the bug on different
 architectures.

 Thibaut has proposed the attached patch.  Would appreciate knowing the
 maintainer's thoughts about the patch.

-- 
Ticket URL: <https://svn.boost.org/trac/boost/ticket/12625>
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