id	summary	reporter	owner	description	type	status	milestone	component	version	severity	resolution	keywords	cc
4445	boost:math::float_advance( 0.0, 2 ) stack overflows if denormal numbers are set to zero	Emmet Spier <emmet.spier@…>	John Maddock	"
If denormal numbers are set to be zero on the processor (register MXCSR bit 6 set) then float_distance( 0.0, any number that is not 1 ) will enter invoke a function recurse which fails to exit and the program will crash with a stack overflow.

Ultimately given the current code, this is because boost::math::sign( denormal number ) == 0 as opposed to the sign of the denormal number.

However, behaviour of this function with denormal numbers really ought to be defined and documented. Possibly a test to see if denormal numbers are disabled needs to be done this case handled appropriately.

Example code, built with optimisations enabled

#include <boost/math/special_functions/next.hpp>

#include <ippcore.h>

int main()
{
  double thisWillWork =  boost::math::float_advance( 0.0, 2 );
  ippSetDenormAreZeros(1); // or set MXCSR bit six directly
  double thisWillStackOverFlow = boost::math::float_advance( 0.0, 2 );
  
  return 0;
}"	Bugs	closed	Boost 1.44.0	math	Boost 1.40.0	Showstopper	fixed