Language: C++

#include <iostream>
#include <complex>
#include <cmath>
#include <vector>
#include <numeric>
#include <functional>
using namespace std;

typedef complex<double> pt;
const double pi = atan(1) * 4;

double f(double m, double s){
	return (s - m) * (s - m);
}

int main(){
	int n;
	while(cin >> n && n){
		vector<double> vec(n);
		for(int i=0;i<n;i++)cin >> vec[i];

		double sum = accumulate(vec.begin(), vec.end(), 0);
		double m = sum / n;

		transform(vec.begin(), vec.end(), vec.begin(), bind1st(f, m));

		double alpha2 = accumulate(vec.begin(), vec.end(), 0) / n;
		double alpha = sqrt(alpha2);

		printf("%.10f\n", alpha);
	}
	return 0;
}

Compiler output:
a.cc: In function 'int main()':
a.cc:25:71: warning: 'std::binder1st<_Operation> std::bind1st(const _Operation&, const _Tp&) [with _Operation = double(double, double); _Tp = double]' is deprecated: use 'std::bind' instead [-Wdeprecated-declarations]
   25 |                 transform(vec.begin(), vec.end(), vec.begin(), bind1st(f, m));
      |                                                                ~~~~~~~^~~~~~
In file included from /usr/include/c++/14/bits/stl_function.h:1435,
                 from /usr/include/c++/14/string:49,
                 from /usr/include/c++/14/bits/locale_classes.h:40,
                 from /usr/include/c++/14/bits/ios_base.h:41,
                 from /usr/include/c++/14/ios:44,
                 from /usr/include/c++/14/ostream:40,
                 from /usr/include/c++/14/iostream:41,
                 from a.cc:1:
/usr/include/c++/14/backward/binders.h:136:5: note: declared here
  136 |     bind1st(const _Operation& __fn, const _Tp& __x)
      |     ^~~~~~~
/usr/include/c++/14/backward/binders.h: In instantiation of 'class std::binder1st<double(double, double)>':
a.cc:25:57:   required from here
   25 |                 transform(vec.begin(), vec.end(), vec.begin(), bind1st(f, m));
      |                                                                ~~~~~~~^~~~~~
/usr/include/c++/14/backward/binders.h:108:11: error: 'double(double, double)' is not a class, struct, or union type
  108 |     class binder1st
      |           ^~~~~~~~~
/usr/include/c++/14/backward/binders.h:114:48: error: 'double(double, double)' is not a class, struct, or union type
  114 |       typename _Operation::first_argument_type value;
      |                                                ^~~~~
/usr/include/c++/14/backward/binders.h:117:7: error: 'double(double, double)' is not a class, struct, or union type
  117 |       binder1st(const _Operation& __x,
      |       ^~~~~~~~~
/usr/include/c++/14/backward/binders.h:122:7: error: 'double(double, double)' is not a class, struct, or union type
  122 |       operator()(const typename _Operation::second_argument_type& __x) const
      |       ^~~~~~~~
/usr/include/c++/14/backward/binders.h:128:7: error: 'double(double, double)' is not a class, struct, or union type
  128 |       operator()(typename _Operation::second_argument_type& __x) const
      |       ^~~~~~~~
/usr/include/c++/14/backward/binders.h:113:18: error: data member 'std::binder1st<double(double, double)>::op' invalidly declared function type
  113 |       _Operation op;
      |                  ^~
a.cc:25:17: error: 'transform' was not declared in this scope
   25 |                 transform(vec.begin(), vec.end(), vec.begin(), bind1st(f, m));
      |                 ^~~~~~~~~
/usr/include/c++/14/backward/binders.h: In instantiation of 'std::binder1st<_Operation> std::bind1st(const _Operation&, const _Tp&) [with _Operation = double(double, double); _Tp = double]':
a.cc:25:57:   required from here
   25 |                 transform(vec.begin(), vec.end(), vec.begin(), bind1st(f, m));
      |                                                                ~~~~~~~^~~~~~
/usr/include/c++/14/backward/binders.h:138:56: error: 'double(double, double)' is not a class, struct, or union type
  138 |       typedef typename _Operation::first_argument_type _Arg1_type;
      |                                                        ^~~~~~~~~~