secant method for nonlinear equations?

Question

Javier Vargas 2017-5-4

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/338615-secant-method-for-nonlinear-equations

Hi I’m supposed to design programs to find roots of nonlinear equations by the Secant method. I have 3 functions and I should work one code with three anonymous function, one for each function (which you selectively activate or deactivate). My problem is that I don’t know how I’m going to activate or deactivate the different anonymous functions and how my program is going to work for 3 completely different functions (not the same variables). Here is what I have for one of the functions. Also is someone can help and tell me if the program is wrong or has error please. clc,clear,close

%The anonymouse function

    f=@(x)x.^5-16*x.^4+95*x.^3-260*x.^2+324*x-144;
    %Graph the function
        ezplot(f);   
        grid on
    %The two guesses 
    a=input('Enter initial guess for smaller bracket');
    b=input('Enter guess for smaller bracket');
    tol=10^-5;
%     the created function
       secant( f,a,b,tol)
    function [ y ] = secant( f,a,b,tol )
     flag=1;
    fa=feval(f,a);
    fb=feval(f,b);
    c= b - (fb/((fb-fa)/(b-a)));
    fc=feval(f,c);
    error= abs((c-b)/c);
    disp('   Xn-1      f(Xn-1)      Xn      f(Xn)      Xn+1     f(Xn+1)    error');
    disp([a fa b fb c fc error]);
        while error > tol
            a = b;
            b = c;
            c = b - (fb/((fb-fa)/(b-a)));
            error= abs((c-b)/c);
            disp([a fa b fb c fc error]);
             flag = flag + 1;
            if(flag == 100)
                break;
            end
        end
    display(['Root is x = ' num2str(c)]);
    y = c;
    end