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  1. #include <iostream>
  2. #include <cmath>
  3. using namespace std;
  4.  
  5. double f(int n)
  6. {
  7.     double x = (1 + pow(5, 0.5)) / 2;
  8.     return (pow(x, n) - pow((x - pow(5, 0.5)), n)) / pow(5, 0.5);
  9. }
  10.  
  11. int main()
  12. {
  13.     cout << "Enter the number... ";
  14.     int a;
  15.     cin >> a;
  16.  
  17.     double z;
  18.     z = f(a);
  19.  
  20.     cout << "n th Fibonacci num is= " << z;
  21.     return 0;
  22. }
Success #stdin #stdout 0s 5284KB
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stdin
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Standard input is empty
stdout
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Enter the number... n th Fibonacci num is= inf
https://ideone.com/PEbl0h
language:
C++ (gcc 8.3)
created:
12 days ago
visibility:
public

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