The FORTRAN program of calculating the Fibonacci numbers is shown below [1]:

PROGRAM fbnc
c	Fibonacci sequence
	integer f1,f2,f3
	f1=1
	f2=1
	write(*,*)'To display Fibonacci numbers.'
	write(*,*)'Enter the number of terms to be displayed:'
	read(*,*)n
	write(*,*)'The Fibonacci sequence is : '
	IF(n.EQ.1)THEN
	write(*,10)f1
10	format(1x,I6)
	ELSE
	write(*,10)f1
	write(*,10)f2
	DO 20 i=3,n
	f3=f1+f2
	write(*,10)f3
	f1=f2
	f2=f3
20	continue
	ENDIF
	STOP
	END

1. Identify all operators (including the End-Of-Statement EOS operators, ) and their frequencies. Put operators names and their frequency values in Table 1below:

TABLE 1: Operators and their Frequencies

No.	Operator	Frequency, f1

Based on this data (from Table 1), estimate total number of unique operators, n1, and the total number of operators appearance, N1:

n1 =

N1 = SUM(f1) =

2. Identify all operands and their frequencies. Put operands names and their frequency values in Table 2 below:

TABLE 2: Operands and their Frequencies

No.	Operand	Frequency, f2

Based on this data (from Table 2), estimate total number of unique operands, n2, and the total number of operands appearance, N2:

n2 =

N2 = SUM(f2) =

3. Following the Halsteads metrics definitions [2-3], estimate the following metrics:

The program length (N): N = N1 + N2

The vocabulary size (n): n = n1 + n2

The program volume (V): V = N * log₂(n)

The difficulty level or error proneness (D) of the program: D = ( n1 / 2 ) * ( N2 / n2 )

The program level (L): L = 1 / D

The effort to implement (E) or understand a program: E = V * D

The time to implement or understand a program (T): T = E / 18

The number of delivered bugs (B): B = ( E^(2/3) ) / 3000 (here the symbol ^ stands for "to the exponent")

4. Make comments on estimates of implementation of this algorithm in any other programming language that you are familiar with.