Matlab - metodo de biseccion

function  m = bisection_foro(f, low, high, tol)

f=inline(f);

% Evaluate both ends of the interval

y1 = feval(f, low);

y2 = feval(f, high);

i = 0;

% Display error and finish if signs are not different

if y1 * y2 > 0

   disp('Have not found a change in sign. Will not continue...');

   m = 'Error';

   return

end

% Work with the limits modifying them until you find

% a function close enough to zero.

disp('Iter    low        high          x0');

while (abs(high - low) >= tol)

    i = i + 1;

    % Find a new value to be tested as a root

    m = (high + low)/2;

    y3 = feval(f, m);

    if y3 == 0

        fprintf('Root at x = %f \n\n', m);

        return

    end

    fprintf('%2i \t %f \t %f \t %f \n', i-1, low, high, m);

    % Update the limits

    if y1 * y3 > 0

        low = m;

        y1 = y3;

    else

        high = m;

    end

end

% Show the last approximation considering the tolerance

w = feval(f, m);

fprintf('\n x = %f produces f(x) = %f \n %i iterations\n', m, y3, i-1);

fprintf(' Approximation with tolerance = %f \n', tol);

forma  de ejecutar.

>> m = bisection_foro('exp(x)-2', 0,2 ,0.0001)

Iter    low        high          x0

 0 	 0.000000 	 2.000000 	 1.000000

 1 	 0.000000 	 1.000000 	 0.500000

 2 	 0.500000 	 1.000000 	 0.750000

 3 	 0.500000 	 0.750000 	 0.625000

 4 	 0.625000 	 0.750000 	 0.687500

 5 	 0.687500 	 0.750000 	 0.718750

 6 	 0.687500 	 0.718750 	 0.703125

 7 	 0.687500 	 0.703125 	 0.695313

 8 	 0.687500 	 0.695313 	 0.691406

 9 	 0.691406 	 0.695313 	 0.693359

10 	 0.691406 	 0.693359 	 0.692383

11 	 0.692383 	 0.693359 	 0.692871

12 	 0.692871 	 0.693359 	 0.693115

13 	 0.693115 	 0.693359 	 0.693237

14 	 0.693115 	 0.693237 	 0.693176

 x = 0.693176 produces f(x) = 0.000058

 14 iterations

 Approximation with tolerance = 0.000100

m =

    0.6932