constexpr

Is is possible to use boost math constants in constexpr? For example, the following line: static constexpr double SEC3 = static_cast<double>(45)/180*boost::math::double_constants::pi; gives me error Error - constexpr variable 'SEC3' must be initialized by a constant expression But if I replace the boost code with simple M_PI, it works fine. I suspect this may be the reason. Coliru gives this error: clang++ -std=c++1y -O2 -Wall -pedantic -pthread main.cpp && ./a.out /usr/local/include/boost/math/constants/constants.hpp:248:52: note: expanded from macro 'BOOST_DEFINE_MATH_CONSTANT' namespace

Following up with this question Having a constexpr static string gives a linker error In the question, this code wasn't able to compile: #include <iostream> struct Test { static constexpr char text[] = "Text"; }; int main() { std::cout << Test::text << std::endl; // error: undefined reference to `Test::text' } From the comment, this code is able to compile: #include <iostream> struct Test { static constexpr auto text = "Text"; }; int main() { std::cout << Test::text << std::endl; } My question is why the auto version works but the array of char version doesn't? Could you please point out the

I'm trying to build a simple sine function using taylor series expansion that can be evaluated at compile time using C++14 constexpr . My code is compiling, but the compiler doesn't generate a constant. sine is defined as follows: template <int P, typename T = double> constexpr T sine(T x) { T result = x; for (int i = 1; i < P; ++i) result += power<T>(-1, i) * power<T>(x, 1 + 2 * i) / factorial<T>(1 + 2 * i); return result; } I can provide code for power and factorial if needed. They are trivial and also constexpr . I'm calling sine from within a loop like this: template <int N> void test

After answering this question and reading this talk and looking at this code , I want to implement constexpr find with just simple array class. Consider following example: #include <cstddef> template <class It, class T> constexpr auto constexpr_find(const It& b, const It& e, T value) { auto begin = b; while (begin != e) { if (*begin == value) break; ++begin; } return *begin; } template<typename T, size_t N> class array { public: typedef T* iterator; typedef const T* const_iterator; constexpr auto begin() const { return const_iterator(array_); } constexpr auto end() const { return const