Chebyshev method for finding root

Question

Milind Amga 2020-10-2

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/603658-chebyshev-method-for-finding-root

评论： Milind Amga 2020-10-2

This code is for finding root of an equation. But this runs into an error saying, unable to convert expression into double array. The error occurs because of the improper use of function handle in g,M,N.

If I take input 'f' as a function handle then I cannot differentiate it and if I take 'f' as just an expression then I cannot convert it into a function handle.

Can someone guide me in the right direction?

Thank you in advance for your time and effort.

function [root,iteration] = chebyshev(a,f) %please input function in terms of y=f(x)(x as independent variable)
% Do not input function as function handle
if nargin<1 % check no of input arguments and if input arguments is less than one then puts an error message
    fprintf('Error! Atleast one input argument is required.');
    return;
end
if nargin<2 % check no of input arguments and if input arguments is less than two then puts a=0
    a=0;
end
g = @(x) f;
M = @(x) diff(f,'x');
N = @(x) diff(f,'x',2);
temp = false;
i =1 ;
x(1) = a;
count = 0;
while temp == false
    A = g(x(i));
    B = M(x(i));
    C = N(x(i));
    D = double((A/B) + 0.5*((A^2)*C/(B^3)));
    x(i+1) = x(i) - D;
    if x(i+1)-x(i) == 0
        temp = true;
        root = x(i-1); 
        iteration = i-1;
        return;
    end
    i = i+1;
    count = count + 1;
end
end