在 C++ 中平均一组复数的正确方法是什么？

Question

我继承了一些需要对一些复数进行平均的 C++ 代码。给定一个集合，它将那些传递条件的值添加到累加器，然后除以添加的值的数量。

使用 gcc（当前为 gcc 8）如果我使用独立 operator/，我会得到 template argument deduction/substitution failed，但它与 std::complex::operator/= 一起工作正常。对于后续维护者来说，这样的细微差别似乎很脆弱。

那么求复数平均值的正确方法是什么？

并且该语言仅部分支持整型除法是否合理？

std::complex<double> A[32] = { /* initialization left to the reader */ };
int count = 0;

std::complex<double> sum;
for (auto i = 0; i < 32; ++i) {
   if ( i % 2 ) { // arbitrary condition, not important
      sum += A[i];
      ++count;
   }
}

auto avg = sum / count; // this is ambiguous
sum /= count;           // this is not

(代表错误，供好奇)

main.cpp: In function ‘int main()’:
main.cpp:16:16: error: no match for ‘operator/’ (operand types are ‘std::complex<double>’ and ‘int’)
 auto avg = sum / count; // this is ambiguous
            ~~~~^~~~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:434:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const _Tp&, const std::complex<_Tp>&)
     operator/(const _Tp& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:434:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   mismatched types ‘const std::complex<_Tp>’ and ‘int’
 auto avg = sum / count; // this is ambiguous
                  ^~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:425:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const std::complex<_Tp>&, const _Tp&)
     operator/(const complex<_Tp>& __x, const _Tp& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:425:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   deduced conflicting types for parameter ‘const _Tp’ (‘double’ and ‘int’)
 auto avg = sum / count; // this is ambiguous
                  ^~~~~
In file included from main.cpp:2:0:
/usr/include/c++/7/complex:416:5: note: candidate: template<class _Tp> std::complex<_Tp> std::operator/(const std::complex<_Tp>&, const std::complex<_Tp>&)
     operator/(const complex<_Tp>& __x, const complex<_Tp>& __y)
     ^~~~~~~~
/usr/include/c++/7/complex:416:5: note:   template argument deduction/substitution failed:
main.cpp:16:18: note:   mismatched types ‘const std::complex<_Tp>’ and ‘int’
 auto avg = sum / count; // this is ambiguous
                  ^~~~~

Answer 1

不确定为它做除法的最正确方法是什么，但如果你仔细查看所有参数 operator/ 和 operator/=，你会注意到：

operator/ 接受 std::complex<T> 或 T.
- 因此，如果您使用 double 创建了原始复合体，那么它应该只接受另一个值，即 double 或 complex<double>。
- 其实取决于你使用的编译器，clang直接给了invalid operands to binary expression ('std::complex<double>' and 'int')错误
operator/=接受std::complex<T>或T，同时也有float、double和[=25的特化=].
- 这意味着传递给 operator/= 的任何内容都将被隐式转换为 float、double 或 long double，而 int 可以做。

在 C++ 中平均一组复数的正确方法是什么？

What is the proper way to average a set of complex numbers in c++?

c++

templates

complex-numbers