MATLAB: Root function does not work:(

doubleroot functionundefined

>> a=[1 2 3];

>> root(a)

Undefined function 'root' for input arguments of type 'double'.

anybody knows why?

   >> roots(a)

Have you defined your own function called "roots"? Try the command

 >> which roots

y=@(x)x.^6-2.*cos(x);
x=linspace(-3,3,100);
plot(x,y(x));
z(1)=fzero(y,-1);
z(2)=fzero(y,1);