On 11/26/2012 02:13 PM, John Maddock wrote:
I'm wandering if this is to be expected, the following code fails if compiled with --fast-math:
//==================================================== #include <boost/math/special_functions/fpclassify.hpp> int main() { const float a = 0.0f/0.0f; assert(not boost::math::isfinite(a)); }
Which fails - does the 0/0 actually yield an infinity? Or is it isfinite that fails?
Either way is hard to make guarentees once you enable an option like that.
The following code: #include <boost/math/special_functions/fpclassify.hpp> int main() { const float a = 0.0f/0.0f; std::cout << "a => " << a << std::endl; std::cout << "boost::math::isfinite(a) => " << boost::math::isfinite(a) << std::endl; std::cout << "a != a: " << (a!=a ? "true" : "false") << std::endl; } gives: a => nan boost::math::isfinite(a) => 1 a != a: true so I believe somehow even with --fast-math it should be possible to make it "working" (if it has to be). Gaetano