fzero: not a valid initial bracketing

format long
y = @(x) 1 - sin(x);
z = @(x) x.^2;
test1 = @(x) (y(x)-z(x));
test2 = @(x) (z(x) - y(x));
ta = 0;
a = 0;
dados = [];
zero = fzero(test1,[0 1])
while (ta != 1)
  a = a + 1;
  y1 = @(x) (a - sin(x));
  funcao = @(x) (y1(x) - z(x));
  intervalo = [0+a 1+a];
  ta = fzero(funcao, intervalo);
  if (ta = 1)
    dados = [dados, a];
  endif
endwhile
disp(dados)

It gives me that error and I don't really know how to fix it. Any help would me appreciated!!

[Torsten]

Your code is weird and in part not MATLAB compatible:

while / endwhile does not exist in MATLAB; it's while / end

ta != 1 has to be replaced by ta ~= 1

if (ta = 1) has to be replaced by if ta==1

Maybe you should explain in your own words what you try to do.

The error message means that the interval you provided as initial guess for fzero does not satisfy that the function, applied to the endpoints of this interval, gives values that differ in sign.