Bisection method

bisect.m

f = @(x) 55*cos(x)-x;
a = 0;
b = 8;
fa = f(a);
fb = f(b); 
if sign(fa) == sign(fb) 
    error('No bracket');
end
while(b-a > 1e-9)
    c = (a+b)/2;
    fc = f(c);
    if sign(f(c)) == sign(f(b)) 
        b = c; fb = fc;
    else 
        a = c; fa = fc;
    end         
end
disp(sprintf('Root found at x = %.9f\n', a));