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Advice on a few bottlenecks in my code

1 vue (au cours des 30 derniers jours)
Matlab2010 le 21 Fév 2013
Clôturé : MATLAB Answer Bot le 20 Août 2021
According to the profiler, I have four lines of code taking up 99% of my CPU time.
pCond = (bold_Phi(k,2) <= data(thisIdx : idx, 7));
pCond = (data(thisIdx : idx, 7) <= bold_Phi(k,2));
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
  4 commentaires
Sean de Wolski
Sean de Wolski le 22 Fév 2013
What is statement?
Matlab2010 le 22 Fév 2013
Modifié(e) : Matlab2010 le 22 Fév 2013
statement is a bool.

Réponses (2)

Kye Taylor
Kye Taylor le 21 Fév 2013
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);
data = rand(1000,1);
isBigIdx = find(data>0.5);
bigData2 = data(isBigIdx);
  1 commentaire
Matlab2010 le 22 Fév 2013
this has helped, but only a little bit. Sped up by c. 10%.

Mark Whirdy
Mark Whirdy le 22 Fév 2013
Modifié(e) : Mark Whirdy le 22 Fév 2013
(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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