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how to find the largest power of 2 that a number is divisible?

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Mnr
Mnr 2015-5-11
回答： Alfonso Nieto-Castanon 2015-5-12
Hello all,
How can I write a code that finds the largest integer power of 2 that a number is divisible? For instance, the largest power of 2 that 12 is divisible, is 4, the largest power of 2 that 20 is divisible is 4 as well, while the largest power of 2 that 24 is divisible is 8. Thanks.

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采纳的回答

per isakson
per isakson 2015-5-11
Hint:
>> factor(12)
ans =
2 2 3

更多回答（2 个）

Joseph Cheng
Joseph Cheng 2015-5-11
You can use the function factor() since it returns the prime factors of the input number. So since it breaks it down to the prime factors the number of 2s being return will make up the largest power of 2 that is still divisible.
x = randi(100);
y = factor(x);
two = y==2;
two = prod(y(two))
disp([x two])
Alfonso Nieto-Castanon
I know this is already answered but the typical/minimal-computation answer for this is:
bitand(x,-x,'int64')
(i.e. find the last 1 in the decimal representation of the original number)

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