use bairstow’s method and matlab to determine the roots of (a) f(x) = −2 + 6.2x − 4x2 + 0.7x3 in matlab

To use Bairstow's method in MATLAB to determine the roots of a polynomial, you can follow these steps:

  1. Define the polynomial function f(x).
  2. Initialize the coefficients of the polynomial you want to find roots for.
  3. Set the desired accuracy for the roots.
  4. Implement the Bairstow's method algorithm.
  5. Test the method by calling the function with the desired polynomial and accuracy.

Here is an example implementation in MATLAB:

main.m
function [roots] = bairstow_method(a, epsilon)
    n = length(a) - 1;  % degree of the polynomial

    % Initialize arrays to store the coefficients
    b = zeros(1, n);
    c = zeros(1, n);

    % Initialize the variables
    error = 1;
    max_iters = 100;
    iter = 0;

    while n > 2 && error > epsilon && iter < max_iters
        iter = iter + 1;

        % Initialize the guess values
        u = complex(rand(), rand());
        v = complex(rand(), rand());

        % Initialize the error terms
        du = complex(0, 0);
        dv = complex(0, 0);

        % Perform the Bairstow's iteration
        while true
            b(n) = a(n) - c(n + 1) * u - c(n + 2) * v;
            for i = n - 1:-1:1
                b(i) = a(i) - b(i + 1) * u - b(i + 2) * v;
            end

            c(n) = b(n) - du * u - dv * v;
            for i = n - 1:-1:1
                c(i) = b(i) - c(i + 1) * u - c(i + 2) * v;
            end

            det = c(2) * c(2) - c(1) * c(3);
            if det == 0
                % Break out of the loop if division by zero
                break;
            end

            % Update the guesses
            du = (b(1) * c(3) - b(2) * c(2)) / det;
            dv = (b(2) * c(1) - b(1) * c(2)) / det;

            % Update the coefficients
            u = u + du;
            v = v + dv;

            % Calculate the error
            error = abs(du) + abs(dv);

            % Break out of the loop if the error is within the desired accuracy
            if error < epsilon
                break;
            end
        end

        % Update the coefficients for the next step
        a = b(3:end);
        n = n - 2;
    end

    % Obtain the remaining roots using quadratic equation
    if n == 2
        roots = roots([a(2) a(1) 1]);
    else
        roots = roots([a(1) 1]);
    end
end
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To find the roots of the polynomial f(x) = -2 + 6.2x - 4x^2 + 0.7x^3 using the Bairstow's method, you can call the bairstow_method function with the coefficients of the polynomial and the desired accuracy. Here's an example usage:

main.m
% Define the polynomial coefficients
a = [0.7 -4 6.2 -2];

% Set the desired accuracy
epsilon = 1e-6;

% Find the roots using Bairstow's method
roots = bairstow_method(a, epsilon);

% Display the roots
disp("The roots are:");
disp(roots);
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When you run this code, MATLAB will display the roots of the polynomial.

I hope this helps you understand how to use Bairstow's method in MATLAB to determine the roots of a polynomial.

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