boost::math, cdf(complement(normal_distribution<>(...)) fails to catch invalid scale and location parameters

[Paul McClellan <paulm@…>]

In boost/math/distributions/normal.hpp:

template <class RealType, class Policy>
inline RealType cdf(const complemented2_type<normal_distribution<RealType, Policy>, RealType>& c)
{
   BOOST_MATH_STD_USING  // for ADL of std functions

   RealType sd = c.dist.standard_deviation();
   RealType mean = c.dist.mean();
   RealType x = c.param;
   static const char* function = "boost::math::cdf(const complement(normal_distribution<%1%>&), %1%)";

   if((boost::math::isinf)(x))
   {
     if(x < 0) return 1; // cdf complement -infinity is unity.
     return 0; // cdf complement +infinity is zero
   }
   // These produce MSVC 4127 warnings, so the above used instead.
   //if(std::numeric_limits<RealType>::has_infinity && x == std::numeric_limits<RealType>::infinity())
   //{ // cdf complement +infinity is zero.
   //  return 0;
   //}
   //if(std::numeric_limits<RealType>::has_infinity && x == -std::numeric_limits<RealType>::infinity())
   //{ // cdf complement -infinity is unity.
   //  return 1;
   //}
   RealType result = 0;
   if(false == detail::check_scale(function, sd, &result, Policy()))
      return result;
   if(false == detail::check_location(function, mean, &result, Policy()))
      return result;
   if(false == detail::check_x(function, x, &result, Policy()))
      return result;

   RealType diff = (x - mean) / (sd * constants::root_two<RealType>());
   result = boost::math::erfc(diff, Policy()) / 2;
   return result;
} // cdf complement

The test if((boost::math::isinf)(x)) occurs before check_scale() or check_location() is called, returning 1 or 0 for infinite x, even if sd or mean are invalid.

The calls to check_scale() and check_location() should be moved up just before the test if((boost::math::isinf)(x)).

See, for example, how the tests are ordered here:

template <class RealType, class Policy>
inline RealType cdf(const normal_distribution<RealType, Policy>& dist, const RealType& x)
{
   BOOST_MATH_STD_USING  // for ADL of std functions

   RealType sd = dist.standard_deviation();
   RealType mean = dist.mean();
   static const char* function = "boost::math::cdf(const normal_distribution<%1%>&, %1%)";
   RealType result = 0;
   if(false == detail::check_scale(function, sd, &result, Policy()))
   {
      return result;
   }
   if(false == detail::check_location(function, mean, &result, Policy()))
   {
      return result;
   }
   if((boost::math::isinf)(x))
   {
     if(x < 0) return 0; // -infinity
     return 1; // + infinity
   }
   // These produce MSVC 4127 warnings, so the above used instead.
   //if(std::numeric_limits<RealType>::has_infinity && x == std::numeric_limits<RealType>::infinity())
   //{ // cdf +infinity is unity.
   //  return 1;
   //}
   //if(std::numeric_limits<RealType>::has_infinity && x == -std::numeric_limits<RealType>::infinity())
   //{ // cdf -infinity is zero.
   //  return 0;
   //}
   if(false == detail::check_x(function, x, &result, Policy()))
   {
     return result;
   }
   RealType diff = (x - mean) / (sd * constants::root_two<RealType>());
   result = boost::math::erfc(-diff, Policy()) / 2;
   return result;
} // cdf

[John Maddock]

(In [85601]) Fix order of error checks. Fixes #9042.

[John Maddock]

(In [85987]) Merge accumulated patches from Trunk. Refs #8384, Refs #8855, refs #9107, refs #9109, refs #8333, refs #8621, refs #8732, refs #8733, refs #8837, refs #8940, refs #9042, refs #9087, refs #9104, refs #9126.