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# Fibonacci problem - Fortran 0

In Brief | This program outputs the sum of all even numbers in the Fibonacci sequence that are smaller than 4 Million |

Language | Fortran |

# 's

` 1! fibonacci.f95`

2! Program to find the sum of all even Fibonacci numbers less than 4 million.

3

4

5program fibonacci

6

7implicit none

8! Define the variables.

9integer i,n(0:2000),sum

10

11print*, 'This program will find the sum of all even Fibonacci numbers'

12print*, 'that have values less than 4 million.'

13

14

15! Initialize the Fibonacci Sequence.

16n(0) = 1

17n(1) = 1

18! Initialize the Sum.

19sum=0

20! Supply the first two lines of output.

21print*, 'Number=', n(0), ' SUM=', sum

22print*, 'Number=', n(1), ' SUM=', sum

23

24do i=2,2000

25! Define the next number in the sequence.

26n(i) = n(i-1) + n(i-2)

27! Exit the loop if the latest number is greater than 4 million.

28if(n(i).ge.4e6) then

29exit

30end if

31! Only add the latest number if it is even.

32if(mod(n(i),2).eq.0) then

33sum=sum+n(i)

34end if

35! Print out the latest fibonacci number and the sum.

36print*, 'Number=', n(i), ' SUM=', sum

37

38end do

39

40print*, 'Fibonacci number now larger than 4 million'

41

42end program fibonacci

This program outputs the sum of all even numbers in the Fibonacci sequence that are smaller than 4 Million

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