Matlab Program for finding positive root of a Non-Linear Function using Newton Rapson Method

a=input('Enter the function =  ', 's');
f= inline(a);
h= diff(a);
d= inline(h);
x(1)=0;
for k=1:inf
    if f(x(1))>0
      for i=2:inf
      x(i)= x(i-1)-((f(x(i-1)))/(d(x(i-1))));
       if abs(x(i)-x(i-1))<=0.001 && x(i)>0  
       Root=x(i)

       break 

       end
       end
       break
     else
      x(1)=x(1)+1;
    end
end