how can i print 2 function?s results ?

the answer is only X and not the niter, why ?

function [X,niter] = bisection2(intervallo,tol)

niter = 1;

if intervallo(1) < intervallo(2)

a = intervallo(1);

b = intervallo(2);

elseif intervallo(1) == intervallo(2)

X = intervallo(2);

else a = intervallo(2);

b = intervallo(1);

end

X0 = (a + b)/2;

if f(a) * f(b) < 0

if abs(f(X0)) < tol

end

while abs (f(X0)) > tol

if f(X0) * f(a) < 0

b = X0;

else

a =X0;

end

X0 = (a + b)/2 ;

niter = niter + 1;

end

X = X0 ;

elseif f(a) * f(b) == 0

if f(a) == 0

X = a;

else

X = b;

end

end

[Azzi Abdelmalek]

How did you call your function, give an example

Answer 1

[Mischa Kim]

Elia, you need to call the function, e.g.,

 [X,niter] = bisection2([1,3],1e-6)

Also, I assume the function f is properly defined. Just in case it is not, try adding

 f = @(x) x^2 - 2;

right after the function declaration.

[Elia]

thanks Mischa but i can't understand some things. The function f is defined in another step and it is function y = f(x)

y = exp(-x)-sin(x);

end and it's ok,but the bisection2 arguments (intervallo,tol) are not constants but input arguments in the main menu. for example, intervallo=[a,b], tol=0.001. in main menu i write

a = input XX;

b = input XX;

tol = input XX;

bisection2([a,b],tol)

and what e.g. means ? thanks

[Mischa Kim]

OK, then you should be fine, simply use (in the main menu)

 a   = input('Input a:   ');
 b   = input('Input b:   ');
 tol = input('Input tol: ');
 [X,niter] = bisection2([a,b],tol)