Im trying to create two new file function base that will get call in my sqroot function. Im getting all types of errors when i try implementing

My code is below the 2 equations im trying to make them into 2 separate file functions are in line 39 and 40. f = x^2-num and df = 2*x

function [sq_root] = sqroot(num)
    format long
    converge = false;
    iter = 0;
    
    %Max allow of error
    esp = 10^-10;
    
    %intial guess
    xn=1;
    %disp('iter, x_n, err_est; err_exact');
    
    tru_err_arr = [];
    est_err_arr = [];
    iter_arr = [];
    
    %Using imporove initial value to find sqrt
    
    if num >= 1
        xn =1;
        while xn^2<num
            xn = xn+10;
        end
        xn = xn/2;
    else
        xn =1;
        while xn^2>num
            xn = xn/10;
        end
        xn = xn*2;
    end
    
    while converge == false
        %Function definations
        f = xn^2-num;
        df = 2*xn;
        %newton_raphson
        nr = xn -(f/df);
        %error defination
        tru_err = sqrt(num)-xn;
        est_err = nr-xn;
        
        tru_err_arr =[tru_err_arr, tru_err];
        est_err_arr =[est_err_arr, est_err];
        
        
        
        %error check
        if abs(est_err/xn)<esp
            converge = true;
        end
        disp([iter, xn,est_err, tru_err]);
        %Iteration counter
        iter_arr = [iter_arr, iter];
        iter = (iter+1);
        xn=[];
        xn=nr;
%----attemp to export to excel------------
        R0 = {'iter','xn', 'est_err', 'tru_err'};
        R1 = iter_arr;
        R2 = xn;
        R3 = est_err_arr;
        R4 = tru_err_arr;
        xlswrite('results.xlsx', R0,'Sheet1','A1');
        xlswrite('results.xlsx', R1,'Sheet1','A2');
        xlswrite('results.xlsx', R2,'Sheet1','B2');
        xlswrite('results.xlsx', R3,'Sheet1','C2');
%-----------------------------------------------
    end
    sq_root = xn;
    disp('Determining the square root of:');
    disp(num);
    disp(['The sqrt of ', num2str(num),' is: ' ]);
    disp(sq_root);
    disp('Number of iteration taken:');
    disp(iter-1);
    info_plot(tru_err_arr, est_err_arr, iter_arr);
    
end

Answer 1

[Ameer Hamza]

Do it like this.

Create a file name fun1.m and write following in it

function y = fun1(xn, num)
    f = xn^2-num;
end

Then create fun2.m and write

function y = fun2(xn)
    f = 2*xn;
end

and then create file sqroot.m and write

function [sq_root] = sqroot(num)
    format long
    converge = false;
    iter = 0;
    
    %Max allow of error
    esp = 10^-10;
    
    %intial guess
    xn=1;
    %disp('iter, x_n, err_est; err_exact');
    
    tru_err_arr = [];
    est_err_arr = [];
    iter_arr = [];
    
    %Using imporove initial value to find sqrt
    
    if num >= 1
        xn =1;
        while xn^2<num
            xn = xn+10;
        end
        xn = xn/2;
    else
        xn =1;
        while xn^2>num
            xn = xn/10;
        end
        xn = xn*2;
    end
    
    while converge == false
        %Function definations
        f = fun1(xn, num);
        df = fun2(xn);
        %newton_raphson
        nr = xn -(f/df);
        %error defination
        tru_err = sqrt(num)-xn;
        est_err = nr-xn;
        
        tru_err_arr =[tru_err_arr, tru_err];
        est_err_arr =[est_err_arr, est_err];
        
        
        
        %error check
        if abs(est_err/xn)<esp
            converge = true;
        end
        disp([iter, xn,est_err, tru_err]);
        %Iteration counter
        iter_arr = [iter_arr, iter];
        iter = (iter+1);
        xn=[];
        xn=nr;
%----attemp to export to excel------------
        R0 = {'iter','xn', 'est_err', 'tru_err'};
        R1 = iter_arr;
        R2 = xn;
        R3 = est_err_arr;
        R4 = tru_err_arr;
        xlswrite('results.xlsx', R0,'Sheet1','A1');
        xlswrite('results.xlsx', R1,'Sheet1','A2');
        xlswrite('results.xlsx', R2,'Sheet1','B2');
        xlswrite('results.xlsx', R3,'Sheet1','C2');
%-----------------------------------------------
    end
    sq_root = xn;
    disp('Determining the square root of:');
    disp(num);
    disp(['The sqrt of ', num2str(num),' is: ' ]);
    disp(sq_root);
    disp('Number of iteration taken:');
    disp(iter-1);
    info_plot(tru_err_arr, est_err_arr, iter_arr);
    
end