Bisection help PLS HELP ME

I have this code for a bisection method but I cant seem to figure out why it wont work I just get this error

every thing else is given

any help is appreciated thanks

Error using  * 
Incorrect dimensions for matrix multiplication. Check that the
number of columns in the first matrix matches the number of rows in
the second matrix. To perform elementwise multiplication, use '.*'.

Error in bisectiona>f (line 65)
x=(2*Fo/wn.^2-w.^2)*sin((wn-w/2)*t)*sin((wn+w/2)*t);

Error in bisectiona (line 14)
    f_left = f(x_left);
function bisectiona
% Bisection method: Used for solving an equation, and finding an
% approximate solution to an equation.
    clc
    % The number of bisection steps
    n = 32;
    % define the initial interval
    a = 41;
    b = 69;
    fprintf('\n initial interval [%g, %g] \n total bisection steps %d\n', a,b,n);
    % Check that a root does exist in the chosen interval
    x_left = a;
    x_right = b;
    f_left = f(x_left);
    f_right = f(x_right);
    if f_left*f_right > 0
    end
    % Bisection: The method
    for i=1:n
        if f_left == 0
            % The exact root of the equation is found at the lower bound
            % of the chosen interval
            fprintf('\n stage %g root %g with zero absolute error \n',i,x_left);
            return;
        end
        if f_right==0
            % The exact root of the equation is found at the upper bound
            % of the chosen interval
            fprintf('\n stage %g root %g with zero absolute error \n',i,x_right);
            return
        end
        % Bisection method: The process
        x_mid = (x_left+x_right)/2.0;
        f_mid = f(x_mid);
        if f_left*f_mid <= 0
            % There is a root in [x_left,x_mid]
            x_right = x_mid;
            f_right = f_mid;
        end
        if f_left*f_mid > 0
            % There is a root in [x_mid,x_right]
            x_left = x_mid;
            f_left = f_mid;
        end
        % Calculate the approximate root for current step
        root = (x_left+x_right)/2.0;
        % Calculate the absolute error for current step
        abs_err=(x_right-x_left)/2.0;
        fprintf('\n stage %g root %g absolute error < %g \n',i,root,abs_err);
    end
    %check satisfaction of equation at end of process
    residual = f(root);
    fprintf('\n final residual = %g \n',residual);
end
    %Created Subfunction to define equation f(x)
function f_value = f(~)
k = 2800;
m = 0.6705;
Fo = 2.0535;
t = 9.177;
x = 0.0253;
w = 77:0.1:80;
wn= sqrt(k/m);
fo= Fo/m;
x=(2*Fo/wn.^2-w.^2)*sin((wn-w/2)*t)*sin((wn+w/2)*t);
f_value = x;
end

Answer 1

[KALYAN ACHARJYA]

"but I cant seem to figure out why it wont work I just get this error"

function f_value=f(~)
k = 2800;
m = 0.6705;
Fo = 2.0535;
t = 9.177;
x = 0.0253;
w = 77:0.1:80;
wn= sqrt(k/m);
fo= Fo/m;
x=(2*Fo/wn^2-w.^2).*sin((wn-w./2)*t).*sin((wn+w./2).*t);
f_value = x;
end

Main Script:

    clc
    clear all;
    close all;
    % approximate solution to an equation.
    % The number of bisection steps
    n = 32;
    % define the initial interval
    a = 41;
    b = 69;
    fprintf('\n initial interval [%g, %g] \n total bisection steps %d\n', a,b,n);
    % Check that a root does exist in the chosen interval
    x_left = a;
    x_right = b;
    f_left=f(x_left);
    f_right=f(x_right);
    if (f_left.*f_right)> 0
    end
    % Bisection: The method
    for i=1:n
        if f_left == 0
            % The exact root of the equation is found at the lower bound
            % of the chosen interval
            fprintf('\n stage %g root %g with zero absolute error \n',i,x_left);
            return;
        end
        if f_right==0
            % The exact root of the equation is found at the upper bound
            % of the chosen interval
            fprintf('\n stage %g root %g with zero absolute error \n',i,x_right);
            return
        end
        % Bisection method: The process
        x_mid = (x_left+x_right)/2.0;
        f_mid = f(x_mid);
        if f_left.*f_mid <= 0
            % There is a root in [x_left,x_mid]
            x_right = x_mid;
            f_right = f_mid;
        end
        if f_left.*f_mid > 0
            % There is a root in [x_mid,x_right]
            x_left = x_mid;
            f_left = f_mid;
        end
        % Calculate the approximate root for current step
        root = (x_left+x_right)/2.0;
        % Calculate the absolute error for current step
        abs_err=(x_right-x_left)/2.0;
        fprintf('\n stage %g root %g absolute error < %g \n',i,root,abs_err);
    end
    %check satisfaction of equation at end of process
    residual = f(root);
    fprintf('\n final residual = %g \n',residual);

Command Window:

Please note: I removed the code errors only.

[madhan ravi]

There are some unnecessary lines of code.