How to pass control from one loop to the other loop

Question

Sai 2015-10-14

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/248589-how-to-pass-control-from-one-loop-to-the-other-loop

编辑： Stephen23 2015-10-16

采纳的回答： Thorsten

在 MATLAB Online 中打开

My aim is to alter a data sample in such a way that the sign of values in between 0.01 to next 0.01 are altered.

Like for example; if given sample is

{0.3,0.21,0.9,0.3,0.01,0.3,0.4,0.32,0.01,0.9,0.97}

My code has to give the output as

{0.3,0.21,0.9,0.3,0.01,-0.3,-0.4,-0.32,0.01,0.9,0.97}

So, I'm trying to write a nested loop to read the sample and alter the sign in between 0.01 to next 0.01

    for n=1:100000
        if u(n)=0.01
           for m=n+1:10000
               if u(m)=0.01
                  % switch to the original 'n' loop
               end
               u(m)=-1*u(m);
           end
        end
    end

But, I'm unable to switch to the original loop. Anyone suggest, how can I switch between them ?

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Answer 1

Thorsten 2015-10-14

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https://ww2.mathworks.cn/matlabcentral/answers/248589-how-to-pass-control-from-one-loop-to-the-other-loop#answer_195956

编辑：Thorsten 2015-10-14

在 MATLAB Online 中打开

invert = 1;
for i = 1:numel(u)
  if u(i) == 0.01
    invert = -invert; 
  elseif invert<0
    u(i) = -u(i); 
  end
end

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Sai 2015-10-15

Thanks for your answer, very simple and elegant :)

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Answer 2

Eng. Fredius Magige 2015-10-14

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https://ww2.mathworks.cn/matlabcentral/answers/248589-how-to-pass-control-from-one-loop-to-the-other-loop#answer_195958

try this

for n=1:100000 if(find(sample(:)==0.01,1)=<find(sample(:)==0.01,2)) % sample is your data num=-1*sample(:,n) else num=sample(:,n) end

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Sai 2015-10-15

Thanks for your suggestion :). It worked

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Answer 3

Stephen23 2015-10-14

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/248589-how-to-pass-control-from-one-loop-to-the-other-loop#answer_195965

编辑：Stephen23 2015-10-14

在 MATLAB Online 中打开

There is no need for slow and inefficient loops when code vectorization is faster and neater:

>> tol = 0.0005;
>> val = 0.01;
>> V = [0.3,0.21,0.9,0.3,0.01,0.3,0.4,0.32,0.01,0.9,0.97];
>> idx = abs(V-val)<tol;
>> idy = mod(cumsum(idx),2);
>> idz = (-1).^(idy&[false,idy(1:end-1)]);
>> V.*idz
ans =
       0.3  0.21   0.9   0.3  0.01  -0.3  -0.4 -0.32  0.01   0.9  0.97