MATLAB: Can’t figure out what I am doing wrong. Looking to find square root using the equation given x=(x+x/a)/2. I also feel like I am not making use of the approximation errors ea and es.

initailizing variableMATLAB

Having trouble determining what I am doing wrong. I don't feel like I am initiallizing x incorrectly, because that is what I am trying to solve for. Not sure if I am making use of ea and es error approximations as well.
code is as follows:
clear
a=input('Enter Number'); %User input number
x=sqrt(a);
ea=100;     %approximate relative error 100 percent 
es=0.01;  %stopping point for error must be less than
count=1;  %iteration beginning 
countmax=1000;  %max number of iterations allowed 
if 0<a          %must be positive number
  while (count<countmax) && (es<ea) %How is es/ea even a factor???
    x=(x+(a/x))/2;    %equation to solve for square root
    disp(x);          %show answer
    x_old=x;
    ea=((x-x_old)/x)*100;
    count=count+1;
  end
else
    msgbox("Enter Positive Number")   %number entered not positive
end

Best Answer

You need to take absolute values,
ea=abs((x-x_old)/x)*100;
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