Re: round-off error in std::pow(std::complex<T>, double) in C++11

[Paolo Carlini]

On 01/25/2013 04:44 PM, Paolo Carlini wrote:
> .. oops, I just noticed what Marc suggested in the PR about changing 
> pow(const complex<>&, const _Tp&) to *actually* forward to the complex 
> builtins when not fast math. That seems a good idea
I have to add to this, however, that unless I did something badly wrong 
in a quick prototype, simply forwarding to the (complex, complex) 
builtin would *not* fix the round-off issue for this specific example. 
In other terms it seems that to actually get 0 we really have to handle 
separately (small) integer exponents, as Marc mentioned in the PR. Then 
again, is this overall a libstdc++ issue or it would make sense to have 
the (..., int) overloads restored at the *ISO* level?

Paolo.