MATLAB: Boling point problem with bisection method

boiling pointhomework

Hi everybody! im trying to solve a boiling problem with bisection method. but there is something wrong.
Question is:
To solve it, i wrote these codes: but there is an error (too many input arguments)
function bisection(a, b, eps)
iter=0; 
  global k A B C
 k=[0.05 0.15 0.5 0.3];
 A=[15.8333 15.8366 15.8737 15.9426];
 B=[2477.07 2697.55 2911.32 3120.29];
 C=[-39.94 -48.78 -56.51 -63.63]; 
 
    xm = (a+b)/2;
    x=[a b xm];
    f = fonk(x);
 for i=1:4
     exp(A-B/(x+C))*k*133.32-1e5;
 end
  
while abs(a-b)>eps 
    if f(1)*f(3) <=0 
        b = xm;
        elseif f(2)*f(3)<=0 
        a = xm;
       else
       disp('You have a ill conditioned function or multiple root'); 
    end
    iter=iter+1;
end
fprintf('Bulunan kök değeri (sürtünme katsayısı) = %8.5f \n', (a+b)/2);
fprintf('%i. iterasyonda sonuca ulaşıldı. \n', iter); 
end
function [f] = fonk(x)
global k A B C
   f=exp(A-B/(x+C))*k*133.32-1e5;
end

Best Answer

Try this code. Check the differences with your code to see the mistakes
x = bisection(300, 400, 0.001);
function xm = bisection(a, b, eps)
    iter = 0;
    global k A B C
    k=[0.05 0.15 0.5 0.3];
    A=[15.8333 15.8366 15.8737 15.9426];
    B=[2477.07 2697.55 2911.32 3120.29];
    C=[-39.94 -48.78 -56.51 -63.63];
    while abs(a-b)>eps
        xm = (a+b)/2;
        
        if fonk(a)*fonk(xm) <=0
            b = xm;
        elseif fonk(xm)*fonk(b)<=0
            a = xm;
        else
            disp('You have a ill conditioned function or multiple root');
        end
        iter=iter+1;
    end
    fprintf('Bulunan kök değeri (sürtünme katsayısı) = %8.5f \n', (a+b)/2);
    fprintf('%i. iterasyonda sonuca ulaşıldı. \n', iter);
end
function [f] = fonk(x)
    global k A B C
    f=sum(exp(A-B./(x+C)).*k*133.32)-1e5;
end
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