When you draw a large loop with
z around its spot, count how many
times
w turns around its
spot.
In
Twizzle Wind Up you might have noticed
this useful fact:
If your large loop encloses all the
z values where
w is zero, then the number of times
w wound around its spot
will tell you how many zeroes there are. This is known as the
winding number .
Suppose
w winds 3 times
around its spot. There will be 3
w -zeroes inside your
z -loop, and the formula for
w must contain
(z-a)(z-b)(z-c) since this
is zero when
z=a or
z=b or
z=c . Now all you have to do is to
look for
a ,
b , and
c inside the loop.