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# Advice on a few bottlenecks in my code

조회 수: 2 (최근 30일)
Matlab2010 2013년 2월 21일
마감: MATLAB Answer Bot 2021년 8월 20일
According to the profiler, I have four lines of code taking up 99% of my CPU time.
if(statment)
pCond = (bold_Phi(k,2) <= data(thisIdx : idx, 7));
else
pCond = (data(thisIdx : idx, 7) <= bold_Phi(k,2));
end
IDY = find( (data(thisIdx : idx, 1) == -1) & (pCond) & (data(thisIdx : idx, 11) == bold_Phi(k,p + 10)) );
IDZ = find( (dV(thisIdx : idx, :) <= -bold_Phi(k,3)) & (pCond) & (sCond) );
where bold_Phi and data are 2D matrices and dV is a vector.
I dont think the time penalty is coming from the indexing as the following statement is very quick
~isnan(data(thisIdx : idx, 3));
anything obvious I have missed that will help me speed up these few statements?
thank you
##### 댓글 수: 4이전 댓글 2개 표시이전 댓글 2개 숨기기
Sean de Wolski 2013년 2월 22일
What is statement?
Matlab2010 2013년 2월 22일
편집: Matlab2010 2013년 2월 22일
statement is a bool.

### 답변 (2개)

Kye Taylor 2013년 2월 21일
If you don't need the actual indices, you can omit the find command to save time. In particular, notice that the following code blocks are equivalent but the first does not use find:
data = rand(1000,1);
isBig = data>0.5;
bigData = data(isBig);
and
data = rand(1000,1);
isBigIdx = find(data>0.5);
bigData2 = data(isBigIdx);
##### 댓글 수: 1이전 댓글 -1개 표시이전 댓글 -1개 숨기기
Matlab2010 2013년 2월 22일
this has helped, but only a little bit. Sped up by c. 10%.

Mark Whirdy 2013년 2월 22일
편집: Mark Whirdy 2013년 2월 22일
(Almost-) Never use the find() function!
I'd need to see the contents of the variables, but at first glance you can maybe just remove it altogether with same functionality?

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