Example 2.  Use Newton's method to solve the nonlinear system  
        [Graphics:Images/NewtonSystemMod_gr_221.gif]    

Solution 2.

First, enter the coordinate functions [Graphics:../Images/NewtonSystemMod_gr_222.gif] and construct the vector function [Graphics:../Images/NewtonSystemMod_gr_223.gif] using Mathematica, and then find the Jacobian matrix [Graphics:../Images/NewtonSystemMod_gr_224.gif].  

[Graphics:../Images/NewtonSystemMod_gr_225.gif]


[Graphics:../Images/NewtonSystemMod_gr_226.gif]
[Graphics:../Images/NewtonSystemMod_gr_227.gif]

[Graphics:../Images/NewtonSystemMod_gr_228.gif]
[Graphics:../Images/NewtonSystemMod_gr_229.gif]
[Graphics:../Images/NewtonSystemMod_gr_230.gif]


Second, graph the curves [Graphics:../Images/NewtonSystemMod_gr_231.gif] and [Graphics:../Images/NewtonSystemMod_gr_232.gif] using Mathematica.  The points of intersection are the solutions we seek.  

[Graphics:../Images/NewtonSystemMod_gr_233.gif]

[Graphics:../Images/NewtonSystemMod_gr_234.gif]

Use the Newton-Raphson method to find a numerical approximation to the solution near [Graphics:../Images/NewtonSystemMod_gr_235.gif].  

[Graphics:../Images/NewtonSystemMod_gr_236.gif]



[Graphics:../Images/NewtonSystemMod_gr_237.gif]

[Graphics:../Images/NewtonSystemMod_gr_238.gif]

[Graphics:../Images/NewtonSystemMod_gr_239.gif]

[Graphics:../Images/NewtonSystemMod_gr_240.gif]

[Graphics:../Images/NewtonSystemMod_gr_241.gif]

A solution to the system satisfies [Graphics:../Images/NewtonSystemMod_gr_242.gif].  Our last approximation is stored in [Graphics:../Images/NewtonSystemMod_gr_243.gif], check it out.  

[Graphics:../Images/NewtonSystemMod_gr_244.gif]


[Graphics:../Images/NewtonSystemMod_gr_245.gif]

[Graphics:../Images/NewtonSystemMod_gr_246.gif]

Accuracy is determined by the tolerance and number of iterations.  How accurate was the solution "really"?

[Graphics:../Images/NewtonSystemMod_gr_247.gif]


[Graphics:../Images/NewtonSystemMod_gr_248.gif]

[Graphics:../Images/NewtonSystemMod_gr_249.gif]

Do you think that iteration produced the solution ? Why ?  

Compare with Mathematica's built in routine.

[Graphics:../Images/NewtonSystemMod_gr_250.gif]


[Graphics:../Images/NewtonSystemMod_gr_251.gif]

[Graphics:../Images/NewtonSystemMod_gr_252.gif]

[Graphics:../Images/NewtonSystemMod_gr_253.gif]

Whose answer is best, ours or Mathematica's ?  How can this be ?  Find out how to increase the number of iterations in Mathematica's subroutine.

[Graphics:../Images/NewtonSystemMod_gr_254.gif]
[Graphics:../Images/NewtonSystemMod_gr_255.gif]

Use the Newton-Raphson method to find a numerical approximation to the solution near [Graphics:../Images/NewtonSystemMod_gr_256.gif].  

[Graphics:../Images/NewtonSystemMod_gr_257.gif]


[Graphics:../Images/NewtonSystemMod_gr_258.gif]

[Graphics:../Images/NewtonSystemMod_gr_259.gif]

[Graphics:../Images/NewtonSystemMod_gr_260.gif]

[Graphics:../Images/NewtonSystemMod_gr_261.gif]

[Graphics:../Images/NewtonSystemMod_gr_262.gif]

A solution to the system satisfies [Graphics:../Images/NewtonSystemMod_gr_263.gif].  Our last approximation is stored in [Graphics:../Images/NewtonSystemMod_gr_264.gif], check it out.  

[Graphics:../Images/NewtonSystemMod_gr_265.gif]


[Graphics:../Images/NewtonSystemMod_gr_266.gif]

[Graphics:../Images/NewtonSystemMod_gr_267.gif]

Do you think that iteration produced the solution ? Why ?  

Compare with Mathematica's built in routine.

[Graphics:../Images/NewtonSystemMod_gr_268.gif]


[Graphics:../Images/NewtonSystemMod_gr_269.gif]

[Graphics:../Images/NewtonSystemMod_gr_270.gif]

[Graphics:../Images/NewtonSystemMod_gr_271.gif]

Whose answer is best, ours or Mathematica's ?  How can this be ?  Find out how to increase the number of iterations in Mathematica's subroutine.

[Graphics:../Images/NewtonSystemMod_gr_272.gif]
[Graphics:../Images/NewtonSystemMod_gr_273.gif]

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004