id,summary,reporter,owner,description,type,status,milestone,component,version,severity,resolution,keywords,cc
12581,cpp_bin_float: Anal fixation. Part 4. Special cases of atan2(),Michael Shatz,John Maddock,"
In following special cases boost::atan2(y, x) return values are different from C RTL:

{{{
  y     x  C RTL  boost
 inf  inf  pi/4   nan
-inf  inf -pi/4   nan
 inf -inf  3*pi/4 nan
-inf -inf -3*pi/4 nan
-0   -val -pi     pi
 0    nan  nan    0
 inf  nan  nan    pi/2
-inf  nan  nan   -pi/2
}}}

The first four boost answer make sense. IMHO, they are better than C RTL answers.
The fifth boost answer is strange, but can be considered acceptable. 
The rest are plain bugs - nan should always propagate.
",Feature Requests,closed,To Be Determined,multiprecision,Boost 1.62.0,Cosmetic,fixed,atan2,