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From: "kariya_mitsuru at hotmail dot com" <gcc-bugzilla@gcc.gnu.org> To: gcc-bugs@gcc.gnu.org Subject: [Bug libstdc++/61795] New: [C++11] return type of std::pow(std::complex<float>, int) should be std::complex<double> Date: Sun, 13 Jul 2014 17:55:00 -0000 [thread overview] Message-ID: <bug-61795-4@http.gcc.gnu.org/bugzilla/> (raw) https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61795 Bug ID: 61795 Summary: [C++11] return type of std::pow(std::complex<float>, int) should be std::complex<double> Product: gcc Version: 4.10.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: libstdc++ Assignee: unassigned at gcc dot gnu.org Reporter: kariya_mitsuru at hotmail dot com With libstdc++, the return type of std::pow(std::complex<float>, int) is std::complex<float>. However, In C++11 mode, the return type of std::pow(std::complex<float>, int) should be std::complex<double>. According to C++11 standard 26.4.9[cmplx.over] paragraph 3, "if either argument has type complex<double>, double, or an integer type, then both arguments are effectively cast to complex<double>." The return type of std::pow(std::complex<double>, std::complex<double>) is std::complex<double>, So I think that std::pow(std::complex<float>, int) should be std::complex<double> in C++11 mode. The sample code below can show whether the return type is std::complex<double>. ================================================================================ #include <iostream> #include <typeinfo> #include <complex> int main() { std::cout << std::boolalpha << (typeid(std::pow(std::complex<float>(1), 1)) == typeid(std::complex<double>)) << std::endl; } ================================================================================ cf. http://melpon.org/wandbox/permlink/zW8TWZe9kKzKWqFq While in C++03 mode, the return type of std::pow(std::complex<float>, int) should be std::complex<float>, I think. Note that this problem does not occur in std::complex<double> and std::complex<long double> because there is no difference between C++03 and C++11. See also: PR56106, PR57974
next reply other threads:[~2014-07-13 17:55 UTC|newest] Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top 2014-07-13 17:55 kariya_mitsuru at hotmail dot com [this message] 2014-07-13 18:29 ` [Bug libstdc++/61795] " daniel.kruegler at googlemail dot com 2014-07-14 3:41 ` kariya_mitsuru at hotmail dot com 2015-04-09 15:43 ` redi at gcc dot gnu.org
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