November 2019
Beginner to intermediate
408 pages
9h 29m
Korean
Content preview from 밑바닥부터 시작하는 비트코인
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밑바닥부터 시작하는 비트코인
56
이런 식으로 음의 지수를 양의 지수로 바꿀 수 있습니다. 이를 그대로 코드로 옮기면 다음과 같
습니다.
class FieldElement:
...
def __pow__(self, exponent):
n = exponent
while n < 0:
n += self.prime - 1
➊
num = pow(self.num, n, self.prime)
➋
return self.__class__(num, self.prime)
➊ 양의 지수를 얻을 때까지
self
.
prim
-
1
값을 계속 더합니다.
➋ 계산 효율이 좋은 내장함수
pow
()
를 사용해서 계산합니다.
그런데
__
pow
__
를 계산하는 더 좋은 방법이 있습니다. 식
a
%
p
에서와 같이 나머지 연산자 (
%
)
를 사용하면 음수인
a
값도
0
과
p
-
1
사이의 값으로 반환됩니다. 따라서 음의 거듭제곱에 대해
서
self
.
prim
-
1
을 계속 더하지 않고
%
연산자를 적용하면
while
루프 없이 코딩할 수 있습
니다. 이런 식으로 구현된
pow
()
함수는 아주 큰 음의 지수를 가진 거듭제곱을 빠르게 실행합
니다.
class FieldElement:
...
def __pow__(self, exponent):
n = exponent % (self.prime - 1)
➊
num = pow
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and much more.
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O’Reilly covers everything we've got, with content to help us build a world-class technology community, upgrade the capabilities and competencies of our teams, and improve overall team performance as well as their engagement.Julian F.
I wanted to learn C and C++, but it didn't click for me until I picked up an O'Reilly book. When I went on the O’Reilly platform, I was astonished to find all the books there, plus live events and sandboxes so you could play around with the technology.Addison B.
I’ve been on the O’Reilly platform for more than eight years. I use a couple of learning platforms, but I'm on O'Reilly more than anybody else. When you're there, you start learning. I'm never disappointed.Amir M.
I'm always learning. So when I got on to O'Reilly, I was like a kid in a candy store. There are playlists. There are answers. There's on-demand training. It's worth its weight in gold, in terms of what it allows me to do.