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fibonacci_numbers.py
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fibonacci_numbers.py
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from itertoolsrecipes import take
from decorators import memoised
def _fibonacci():
a, b = 0, 1
while True:
yield a
a, b = b, a + b
def fibonacci_numbers(n=None):
if n is not None:
return take(n, _fibonacci())
else:
return _fibonacci()
@memoised
def fibonacci_number(num):
'''Recursive definition from:
http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-001-structure-and-interpretation-of-computer-programs-spring-2005/video-lectures/1b-procedures-and-processes-substitution-model/
'''
if num < 0:
raise ValueError('Fibonacci numbers not defined for negative numbers.')
if num < 2:
return num
else:
return fibonacci_number(num-2) + fibonacci_number(num-1)
if __name__ == "__main__":
print('Fibonacci Sequence:\n')
print('First Few:')
for num in fibonacci_numbers(13):
print(num)
print()
from time import sleep
print('Infinite (Ctrl-C to exit):')
for num in fibonacci_numbers():
print(num)
sleep(.42)