How to find a real positive root

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Atom 2013-4-15

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https://ww2.mathworks.cn/matlabcentral/answers/72120-how-to-find-a-real-positive-root

How to find only the positive root of the equation x^3-A=0 for each A where A is a parameter varying like 1,2,3,....1000.

If alpha is the root, find the value of alpha/(alpha +1) for each case.

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Answer 1

Youssef Khmou 2013-4-15

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https://ww2.mathworks.cn/matlabcentral/answers/72120-how-to-find-a-real-positive-root#answer_82317

编辑：Youssef Khmou 2013-4-15

在 MATLAB Online 中打开

hi, try this essay :

 counter=1;
 for A=1:100
   f=@(x) x^3-A;
   alpha=fzero(f,A);
   if isa(alpha,'complex');
        continue;
  else
  X(counter)=alpha;
  Y(counter)=alpha/(alpha+1);
  counter=counter+1;
 end
 end
 figure, plot(Y);

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Atom 2013-4-15

编辑：Atom 2013-4-15

Thanks for your answer. If the equation is of higher degree having -ve root, then how to avoid the negative root as well in order to get only the positive root?

Youssef Khmou 2013-4-16