Why is my while loop stopping after one loop?

I'm trying to find the root of a polynomial that's closest to my guess. My guess is supposed to keep running through the loop until it is within 6 decimals of accuracy of the actual root. But it stops after 1 loop. Please help!!

Here's part of my script:

    dpolyvec=polyder(polyvec);
    x=guess;      
    actual=roots(polyvec);
    count=0;
    notDone=1;    

    while notDone

        if dpolyvec==0
            notDone=0
        end

        x=x-(polyval(polyvec,x)./polyval(dpolyvec,x));

        if x<(actual-10^(-6))        
            notDone=0;               
        end

        if x<(actual+10^(-6))
            notDone=0;
        end

        count=count+1;

        if count>500
            notDone=0;
        end

    end

Answer 1

[Image Analyst]

Try this: http://blogs.mathworks.com/videos/2012/07/03/debugging-in-matlab/ and you'll see that evidently you're stepping into one of the blocks that sets notDone = 0.