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Is there a way to reduce compilation time for this segment?

Asked by Souheil Araoud on 8 Sep 2019
Latest activity Commented on by Souheil Araoud on 8 Sep 2019
tic
iscorr = 1;
myunc = zeros(1,length(Kurzschluss.Plateaus_I));
myfunction = '(X2/X1)*(sqrt(1 - X3^2/(X2^2 * X1^2)))';
for i=1:length(mystruct.Plateaus_I)
x1 = mystruct.Plateaus_I{1,i};
x2 = mystruct.Plateaus_U{1,i};
x3 = mystruct.Plateaus_P{1,i};
myunc(i) = calculateEndUncertainty_3(x1,x2,x3,iscorr,myfunction);
end
toc

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function [unc] = CalculateEndUncertainty_3(x1,x2,x3,iscorr,myfunction)
N = 3;
if iscorr
Enable_correlation = 1;
else
Enable_correlation = 0;
end
StrModelFunction = myfunction;
StrInput = '';
StrMean = '';
for c1 = 1:N
StrInput = [StrInput 'X' num2str(c1) ','];
StrMean = [StrMean 'mean(x' num2str(c1) '),'];
end
StrInput(end) = [];
StrMean(end) = [];
eval(['syms f(' StrInput ')'])
eval(['f(' StrInput ') =' StrModelFunction ';'])
u2 = 0;
for c1 = 1:N
temp = diff(f,eval(['X' num2str(c1)]));
df_dx = double(eval(['temp(' StrMean ')']));
u2 = u2 + df_dx^2*std(eval(['x' num2str(c1)]))^2/length(x1) ;
end
if Enable_correlation
for c1 = 1:N-1
for c2 = c1+1:N
temp_c1 = diff(f,eval(['X' num2str(c1)]));
df_dx_c1 = double(eval(['temp_c1(' StrMean ')']));
temp_c2 = diff(f,eval(['X' num2str(c2)]));
df_dx_c2 = double(eval(['temp_c2(' StrMean ')']));
temp = cov(eval(['x' num2str(c1)]),eval(['x' num2str(c2)]));
u2 = u2 + 2*df_dx_c1*df_dx_c2*temp(2)/length(x1);
end
end
end
unc = sqrt(abs(u2));
res = double(eval(['f(' StrMean ')']));
end
You have a lot of eval() that is why script is slow
The function below depends on f(), temp(), temp_c1(), temp_c2()
Maybe you can attach whole your project? Any description?
The whole project is way too long. This function is supposed to take 3 inputs of a function as vectors (in my case containing about 5 lightly diffefrent values) and calculate the uncertainty of the result based on the mean value of each input vector etc.. The function has been applied on 3 unidimensional cells named Plateaus_I, Plateaus_U and Plateaus_P containing a vector in each cell.

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R2015b

2 Answers

Answer by darova
on 8 Sep 2019
 Accepted Answer

See if it works

  1 Comment

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Answer by Jackson Burns on 8 Sep 2019

Hi Souheil!
If you have access to the parallel computing toolbox, you can improve execution time with a parfor loop.
tic
iscorr = 1;
myunc = zeros(1,length(Kurzschluss.Plateaus_I));
myfunction = '(X2/X1)*(sqrt(1 - X3^2/(X2^2 * X1^2)))';
parfor i=1:length(mystruct.Plateaus_I)
x1 = mystruct.Plateaus_I{1,i};
x2 = mystruct.Plateaus_U{1,i};
x3 = mystruct.Plateaus_P{1,i};
myunc(i) = calculateEndUncertainty_3(x1,x2,x3,iscorr,myfunction);
end
toc
Other optimizations will likely come from improving your functions, such as calculateEndUncertainty_3. This page from MathWorks has some great advice on how to do this. I would reccomend looking at vectorization in particular, as MATLAB is extremely powerful when properly vectorized.
Hope this helps, good luck!

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