June 2018
Beginner to intermediate
304 pages
7h 38m
Korean
Content preview from 우아한 사이파이: 수학, 과학, 엔지니어링을 위한 파이썬 데이터 분석 라이브러리 SciPy
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127
4
장
주파수와 고속 푸리에 변환
4.4
푸리에 변환 구현
사이파이의 이산 푸리에 변환 함수는
scipy
.
fftpack
모듈에 있다. 다음과 같은 이산 푸리에 변
환 함수를 제공한다.
●
fft
,
fft2
,
fftn
1
,
2
혹은
n
차원의 고속 푸리에 변환 알고리즘을 사용하여 이산 푸리에 변환을 계산한다.
●
ifft
,
ifft2
,
ifftn
역 이산 푸리에 변환을 계산한다.
●
dct
,
idct
,
dst
,
idst
cos
변환, 역
cos
변환,
sin
변환, 역
sin
변환을 계산한다.
●
fftshift
,
ifftshift
0
-주파수 성분을 스펙트럼의 중심으로 이동하거나 뒤로 이동한다 (이번 장 뒤에서 자세한 내용을 살펴본다 ).
●
fftfreq
이산 푸리에 변환 샘플 주파수를 반환한다.
넘파이의 아래 함수로 위의 사이파이 함수를 보완한다.
●
테이퍼드(
Tapered
) 윈도우 함수들
np
.
hanning
,
np
.
hamming
,
np
.
bartlett
,
np
.
blackman
,
np
.
kaiser
이산 푸리에 변환은 입력이 큰 고속 합성곱을 수행하는데, 이때
scipy
.
signal
.
fftconvolve
( )
함수를 사용한다.
사이파이는 포트란
FFTPACK
라이브러리를 래핑
wrapping
한다.
FFTPACK
라이브러리는
FFTW
패키지와 같은 빠른 속도는 아니지만 퍼미시브 자유 소프트웨어 라이선스다.
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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.