func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int T, n;     cin >> T;     double R1, R2, R3;     while (T--) {       scanf( %lf%lf%d , &R1, &R2, &n);       R3 = R1 - R2;       double k1 = -1 / R1;       double k2 = 1 / R2;       double k3 = 1 / R3;       double k4 = k1 + k2 + k3;       double ans;       for (int i = 1; i <= n; i++) {         double R4 = 1 / k4;         ans = R4;         double k5 = 2 * (k1 + k2 + k4) - k3;         k3 = k4;         k4 = k5;       }       printf( %0.10lf n , fabs(ans));     }     return 0;   }   