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.

Answer 1

[Youssef Khmou]

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);

[Atom]

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]

add the condition : if isa(alpha,'complex') && (g>=0)