profiling.cpp

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#include <iostream>
#include "mathlib.h"
 
using namespace std;
using namespace mathlib;
 
int main() {
 
        MathError err;
        double mean = 0.0; 
        double M2 = 0.0;
        int n = 0;
        double x;
 
        while(cin >> x) {
        
            n++;
 
            double delta = subtract(x, mean);
            mean = add(mean, divide(delta, (double)n, err));
            M2 = add(M2, multiply(delta, subtract(x, mean)));
        }
 
        if(n < 2) {
            cout << "Error: not enough data" << endl;
            return 1;
        }
 
        double variance = divide(M2, subtract((double)n, 1.0), err);
        double stddev = root(variance, 2, err);
 
        cout << stddev << endl;
 
        return 0;
}