Matlab Program for finding positive root of a Non-Linear Funtion using Secant Method

a=input('Enter the function =  ', 's');
f= inline(a);
x(1)=0; x(2)=1;iteration=0;
for k=1:inf
 if f(x(1))*f(x(2))<0
  for i=3:inf
  x(i)=(x(i-2)*(f(x(i-1)))-x(i-1)*(f(x(i-2))))/(f(x(i-1))-f(x(i-2)));
  iteration=iteration+1;
    if abs(x(i)-x(i-1))<=0.001 && x(i)>0
    root=x(i)
    iteration=iteration
    break
    end
  end
  break
 else
 x(1)=x(1)+1;
 x(2)=x(2)+1;
 end
end