A simple Fibonacci sequence solver.

fibo-solver.py

'''
written by: Bryan Angelo
'''

def fibCount(nth=0,ntp=0,sus=False): # where / limit / yield
	# infinite loop
	A,B = 1,1
	nth_ = 0
	while 1:
		if bool(nth): # last number of specific iteration limit
			if nth_ == nth:
				yield B
		elif bool(ntp): # return iteration count and nearest number reached
			if B >= ntp:
				yield (nth_, B)
		elif bool(sus): # continuous computation
			yield B
		
		X = A + B
		A = B
		B = X
		nth_ += 1


def isFibonacci(n):
	# A utility function that returns true if x is perfect square 
	def isPerfectSquare(x):
		s = None if x < 0 else x**0.5
		# Returns true if n is a Fibinacci Number, else false
		return s*s == x 
	# n is Fibinacci if one of 5*n*n + 4 or 5*n*n - 4 or both is a perferct square 
	return isPerfectSquare(5*n*n + 4) or isPerfectSquare(5*n*n - 4)


if __name__ == "__main__":
	import time
	print(isFibonacci(5)) # determine if fibonacci number
	time.sleep(1)
	print(next(fibCount(nth=10))) # last number of specific iteration limit
	time.sleep(1)
	print(next(fibCount(ntp=10))) # return iteration count and nearest number reached
	time.sleep(1)
	for i in fibCount(sus=True): # continuous computation
		print(i)