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clarle/closest_mersenne.py

Last active June 7, 2016 16:20
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Closest Mersenne function - optimized for readability, not performance
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closest_mersenne.py
from math import log
def round_base_2(n):
return 2**round(log(n)/log(2))
def closest_mersenne(n):
rb2 = round_base_2(n)
# We got the closest power of 2, so you can just drop the first digit and replace all others with 1
result = bin(rb2)[3:].replace('0', '1')
return int(result, 2)
n = 16777214
print("The closest Mersenne to {} is {}.".format(n, closest_mersenne(n)))
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