Solution is going to infinite iterations
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I am getting infinite iterations, please help me.
clear all
a=0.5;
err=1e-6;
count=0;
x=100;
%fx = a-cos(a);
%dfx= 1+sin(a);
%x1=a-(fx/dfx);
while abs(a-x)>err
fx=x-cos(x);
dfx= 1+sin(x);
x1=x-(fx/dfx);
%x=abs(x1-x);
%x=x1;
if abs(x1-a)>err
x=x1;
%elseif abs(a-x1)>err
% continue
end
count = count + 1;
sprintf('After iteration %2.0d the x is %3.15f',count,x)
end
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Answers (1)
Torsten
on 4 Aug 2017
Edited: Torsten
on 4 Aug 2017
Your decision variable in the while statement must be
abs(fx)> err
and/or
abs(x1-x)>err
but not
abs(x1-a)>err
Note that 0.5 is not a root of f(x)=x-cos(x).
Best wishes
Torsten.
2 Comments
Torsten
on 7 Aug 2017
After the commands in the while-loop have been executed, MATLAB checks the exit condition and exits if they are no longer true. Since you set x=x1 at the end of the while-loop, the condition to exit (abs(x-x1)<=err) will be satisfied after the first iteration. The remedy is to set x=x1 at the start of the while-loop.
Best wishes
Torsten.
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