How to find a circle segment within a matlab function

I need to create a function that will find the length of the arc of a circle which is 2 times the length of the segment AB that is reuniting both ends of the arc. Here is my function but I know that within the loop «for» there is a mistake but I can't see where.

The function «func» is where my angle in rad is multiplied by the radius divided by 2 (i suppose this is the good function considering the informations mentionned before).

function [rep]=Arcb(theta)

Ea=1.0;
Er=0.00001;
itermax=25;
i=0;
r=1;
iflag=0;

for i=1:itermax
    func=(theta)*r/2;
    dfunc=r/2;
    theta2=theta-(func/dfunc);
    Ea=abs((theta2-theta)/theta);
    if Ea<=Er
        rep=theta2;
        fprintf('La solution après %d itérations est %5.2\n',i,rep);
        iflag=1;
        break
    else
        rep=theta;
    end
end
end

[Dyuman Joshi]

Please format your code properly.

Regardless of the (finite) value of theta, theta2 will always be zero -

func=(theta)*r/2;
dfunc=r/2;
theta2=theta-(func/dfunc);

Answer 1

[Image Analyst]

A diagram sure would have helped. Without it about all I can suggest is the FAQ:

https://matlab.fandom.com/wiki/FAQ#How_can_I_fit_a_circle_to_a_set_of_XY_data?

https://matlab.fandom.com/wiki/FAQ#How_do_I_create_an_arc?

or the attached paper.

If you have any more questions, then attach your data and code to read it in with the paperclip icon after you read this:

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