Lab for the Newton-Raphson Method
Module for Newton's Method

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Newton-Raphson Iteration. Find a root of f(x) = 0 given an initial approximation [Graphics:nr.txtgr1.gif] using the iteration: [Graphics:nr.txtgr2.gif].

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr3.gif]
 
 

Report to be handed in.
Computer Exercises.



Exercise 1. Use Newton's method to find the three roots of the cubic polynomial
[Graphics:nr.txtgr5.gif].
Use the starting values [Graphics:nr.txtgr6.gif]. For each different starting value, explain what happened. Supply graphs and lists of iterations in your solution. Determine the Newton-Raphson formula
[Graphics:nr.txtgr7.gif]that is used. Show details of the computations starting with [Graphics:nr.txtgr8.gif].

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr9.gif]

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr10.gif]

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr11.gif]

Starting with [Graphics:nr.txtgr12.gif], type the following list of commands which perform Newton's method.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr13.gif]

Now use the subroutine with the various starting values [Graphics:nr.txtgr14.gif].

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr15.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr16.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr17.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr18.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr19.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr20.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr21.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr22.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr23.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr24.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr25.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr26.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr27.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr28.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr29.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr30.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr31.gif]

How many iterations did it take to converge starting with [Graphics:nr.txtgr32.gif] ?
What was the final approximation to the root ?
Adjust the number of iterations used so that unnecessary values are not printed.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr33.gif]
[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr34.gif]

Exercise 2. Use Newton's method to find all the roots of the cubic polynomial
[Graphics:nr.txtgr35.gif].
Supply graphs and lists of iterations in your solution.

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr36.gif]

[Graphics:nr.txtgr4.gif][Graphics:nr.txtgr37.gif]

 

 

 

(c) John H. Mathews, 1998