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Advice on a few bottlenecks in my code

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Matlab2010
Matlab2010 el 21 de Feb. de 2013
Cerrada: MATLAB Answer Bot el 20 de Ag. de 2021
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
  4 comentarios
Sean de Wolski
Sean de Wolski el 22 de Feb. de 2013
What is statement?
Matlab2010
Matlab2010 el 22 de Feb. de 2013
Editada: Matlab2010 el 22 de Feb. de 2013
statement is a bool.

Respuestas (2)

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

Mark Whirdy
Mark Whirdy el 22 de Feb. de 2013
Editada: Mark Whirdy el 22 de Feb. de 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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