MATLAB: Devi method of finding root

plz find the attachment and

help me in executing this program

Best Answer

Dear Unhappy, here is the solution if I understood your problem correctly:

syms a_sym b_sym
x_sym = a_sym + 1j * b_sym;
a = 1;
b = 2;         
e = 2.71828;                
tol = 1e-5;                      
da = e + a;
db = e + b  ;                  
count = 0;                      
while (~(abs(da) < tol) && ~(abs(db) < tol))
    f = double(subs(x_sym, [a_sym b_sym], [a b]));
    realF = real(f);
    imagF = imag(f);
    da = (realF * realF + imagF * imagF) / abs(f^2);
    db = (realF * realF - imagF * imagF) / abs(f^2);
    a = a - da;      
    b = b - db;
    count = count + 1;          
    if (count > 400)
        fprintf('Error...! Solution not converging !!! \n');  % printing the error message
        break;
    end
end
if (count < 400)
    fprintf('The solution = '); 
    fprintf('\nNumber of iteration taken = %d\n',count);
end

Related Solutions

MATLAB: I cannot get the error.

a(x)=(1/2)*(cos(x)+3);

That defines a as being a symbolic function

a(b)= vpa(a(b))

That attempts to define the value of the function evaluated at b, but MATLAB does not permit you to define a general function and then assign values to the function at specific locations.

Below is the code rewritten in a way that is acceptable to MATLAB:

 syms f(x) a(x)
f(x)=(cos(x)-(2*x)+3);
a(x)=(1/2)*(cos(x)+3);
da=diff(a,x);
b=pi/2.5;
 s='a                    f(x)';
 
 disp(s);
 
for i=(1:100)
    
     if  abs(vpa(da(b)))<1  
    
    if vpa(f(a(b)))~=0
            
        a(x) = piecewise(x==b, vpa(a(b)), a(x));
        
        f(x) = piecewise(x == b, vpa(f(b)), f(x));
        
            A=[num2str(double(a(b))),'            ',num2str(double(f(b)))];
            
            
            disp(A);
            
           a(x)= piecewise(x==b, vpa(a(a(b))), a(x));
            
            i=i+1;
            
        elseif vpa(f(b))==0
           
            a(x)= piecewise(x==b, vpa(a(b)), a(x));
        
        f(x) = piecewise(x == b, vpa(f(b)), f(x));
            
            A=[num2str(doubble(a(b))),'               ',num2str(double(f(b)))];
            
          disp(A);
          
    end
    
     else 
         
         a(x) = piecewise(x==b, vpa(a(a(b))), a(x));
            
            i=i+1;
        
     end
    
end

I made no attempt at all to correct the algorithm: I just corrected the syntax to make it do exactly what you coded.

MATLAB: How to set a function for error propagation

Yes you need to deinfe a b da and db either in the function or in your script before you call the function and also let them be inputs to your function

like this:

function [DeltaY] = equation(x,a,b,da,db)
DeltaY = sqrt((diff x,a)^2 * da^2 + (diff x,b)^2 * db^2)
end

Best Answer

Related Solutions

MATLAB: I cannot get the error.

MATLAB: How to set a function for error propagation

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