C++11 cmath functions not in std namespace for android NDK w/gcc-4.8 or clang 3.4

Question

After C++11, various cmath functions previously in the global namespace are moved to the std namespace, when including the h

Answer 1

If functions are really missing, you have to write them yourself (or copy them from some other implementation).

In the Android NDK, some functions seem to be there, but just outside of namespace std. I have worked around the same issue for the round function by adding a function round to namespace std, which just falls back on the round function from the global scope.

namespace std
{
    inline int round(float x)
    {
        return ::round(x);
    }
}

If you want to use this in a portable way, you would have to protect this with preprocessor macros.