Re: [Boost-bugs] [Boost C++ Libraries] #13360: std::numeric_limits<multiprecision::float128> methods fail to compile in C++11 mode

Subject: Re: [Boost-bugs] [Boost C++ Libraries] #13360: std::numeric_limits<multiprecision::float128> methods fail to compile in C++11 mode
From: Boost C++ Libraries (noreply_at_[hidden])
Date: 2017-12-28 21:16:49

#13360: std::numeric_limits<multiprecision::float128> methods fail to compile in
C++11 mode
-------------------------------+----------------------------
  Reporter:  b7.10110111@…     |      Owner:  John Maddock
      Type:  Bugs              |     Status:  new
 Milestone:  To Be Determined  |  Component:  multiprecision
   Version:  Boost 1.66.0      |   Severity:  Regression
Resolution:                    |   Keywords:
-------------------------------+----------------------------

Comment (by b7.10110111@…):

 Actually, if we want to remain compatible to non-x87 FPUs, supporting
 IEEE754 binary64 as {{{double}}}, then we can do it this way:
 {{{
     constexpr auto max=(__float128(0x1.fffffffffffffp+1023)
                         + 0x1.ffffffffffffp+970 + 0x1.ffcp+921)
                        * 0x1p+1023 * 0x1p+1023 * 0x1p+1023 * 0x1p+1023
                        * 0x1p+1023 * 0x1p+1023 * 0x1p+1023 * 0x1p+1023
                        * 0x1p+1023 * 0x1p+1023 * 0x1p+1023 * 0x1p+1023
                        * 0x1p+1023 * 0x1p+1023 * 0x1p+1023 * 0x1p+15;
     constexpr auto min=__float128(0x1p-1022) * 0x1p-1022
                        * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                        * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                        * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                        * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                        * 0x1p-1022 * 0x1p-1022 * 0x1p-30;
     constexpr auto denorm_min=__float128(0x1p-1022) * 0x1p-1022
                               * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                               * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                               * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                               * 0x1p-1022 * 0x1p-1022 * 0x1p-1022
                               * 0x1p-1022 * 0x1p-1022 * 0x1p-142;
     constexpr auto epsilon=__float128(0x1p-112);

 assert(max==std::numeric_limits<boost::multiprecision::float128>::max());
 assert(min==std::numeric_limits<boost::multiprecision::float128>::min());
 assert(epsilon==std::numeric_limits<boost::multiprecision::float128>::epsilon());
 }}}

-- 
Ticket URL: <https://svn.boost.org/trac10/boost/ticket/13360#comment:4>
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