The main idea of Neville's algorithm is to approximate the value of a polynomial at a particular point without having to first find all of the coefficients of the polynomial. The following examples and exercise illustrate how to use this method.
Approximate the function at using , , and .
We begin by finding the value of the function at the given points, , and . We obtain
- and
- .
Since, we know from the Wikipedia page on Neville's Algorithm that , the approximations for , and are
- and
- .
Using Neville's Algorithm we can now calculate and . We find and to be
and
From these two values we now find to be
Thus, our approximation for the function at using , and is . We know the actual value of the function evaluated at is or . Therefore, our approximation within of the actual value.
For this example, we will use the points given in the example of Newton form to approximate the function at . The given points are
- and
- .
Using , the approximations for , and are
- and
- .
Using Neville's Algorithm we now calculate and to be equal to
From these two values we find to be
Try this one on your own before revealing the answer. You can reveal one step at a time.
Approximate the function at using , and .
We begin by evaluating the function at four given points and obtain
- and
- .
Thus, and .
We can calculate and to be
From these values we now find , and and get
- .
Finally, we can find to be
http://people.math.sfu.ca/~kevmitch/teaching/316-10.09/neville.pdf