ernie.WPI.EDU> cat class17a.C

// file class17a.C, cs2223, D97/98 //
// Fibonacci sequence using recursive function calls

// 09Apr08 NW, First version

// includes
#include "headers.h"
#include "Timer.h" // see Class 2

// definitions
#define FIB_MAX 35 // anything larger takes too long

// prototype
long int fib(int); // Fibonacci sequence

// main
int main ()
	{
	Timer *timer;
	for (int n = 0; n <= FIB_MAX; n++)
		{
		timer = new Timer(n);
		cout << "n = " << n << "  fib(n) = " << fib(n) << endl;
		delete timer; // print out the time
		cout << endl;
		}
	return 0;
	} // end main()

long int fib(int n) // Fibonacci sequence
	{
	if (n <= 0) return 0;
	if (n == 1) return 1;
	return fib(n-1) + fib(n-2);
	} // end fib()

// Copyright 1998 Norman Wittels

ernie.WPI.EDU> g++ class17a.C Timer.C

ernie.WPI.EDU> a.out

n = 0  fib(n) = 0
Process 0 took 0 seconds

n = 1  fib(n) = 1
Process 1 took 0 seconds

n = 2  fib(n) = 1
Process 2 took 0 seconds

n = 3  fib(n) = 2
Process 3 took 0 seconds

n = 4  fib(n) = 3
Process 4 took 0 seconds

n = 5  fib(n) = 5
Process 5 took 0 seconds

n = 6  fib(n) = 8
Process 6 took 0 seconds

n = 7  fib(n) = 13
Process 7 took 0 seconds

n = 8  fib(n) = 21
Process 8 took 0 seconds

n = 9  fib(n) = 34
Process 9 took 0 seconds

n = 10  fib(n) = 55
Process 10 took 0 seconds

n = 11  fib(n) = 89
Process 11 took 0 seconds

n = 12  fib(n) = 144
Process 12 took 0 seconds

n = 13  fib(n) = 233
Process 13 took 0 seconds

n = 14  fib(n) = 377
Process 14 took 0 seconds

n = 15  fib(n) = 610
Process 15 took 0 seconds

n = 16  fib(n) = 987
Process 16 took 0 seconds

n = 17  fib(n) = 1597
Process 17 took 0 seconds

n = 18  fib(n) = 2584
Process 18 took 0 seconds

n = 19  fib(n) = 4181
Process 19 took 0 seconds

n = 20  fib(n) = 6765
Process 20 took 0 seconds

n = 21  fib(n) = 10946
Process 21 took 0 seconds

n = 22  fib(n) = 17711
Process 22 took 0.016666 seconds

n = 23  fib(n) = 28657
Process 23 took 0 seconds

n = 24  fib(n) = 46368
Process 24 took 0.016666 seconds

n = 25  fib(n) = 75025
Process 25 took 0.033332 seconds

n = 26  fib(n) = 121393
Process 26 took 0.033332 seconds

n = 27  fib(n) = 196418
Process 27 took 0.099996 seconds

n = 28  fib(n) = 317811
Process 28 took 0.099996 seconds

n = 29  fib(n) = 514229
Process 29 took 0.183326 seconds

n = 30  fib(n) = 832040
Process 30 took 0.299988 seconds

n = 31  fib(n) = 1346269
Process 31 took 0.483314 seconds

n = 32  fib(n) = 2178309
Process 32 took 0.74997 seconds

n = 33  fib(n) = 3524578
Process 33 took 1.26662 seconds

n = 34  fib(n) = 5702887
Process 34 took 1.99992 seconds

n = 35  fib(n) = 9227465
Process 35 took 3.31653 seconds

ernie.WPI.EDU>