Example 8.16.  Evaluate  [Graphics:Images/IntegralsRationalMod_gr_86.gif].  

[Graphics:Images/IntegralsRationalMod_gr_87.gif]

Explore Solution 8.16.

Enter the function  [Graphics:../Images/IntegralsRationalMod_gr_94.gif]  and locate the singularities.

[Graphics:../Images/IntegralsRationalMod_gr_95.gif]





[Graphics:../Images/IntegralsRationalMod_gr_96.gif]

 

 

 

Which poles lie in the upper half plane ?

[Graphics:../Images/IntegralsRationalMod_gr_97.gif]



[Graphics:../Images/IntegralsRationalMod_gr_98.gif]

[Graphics:../Images/IntegralsRationalMod_gr_99.gif]

 

 

 

Compute the residues at  [Graphics:../Images/IntegralsRationalMod_gr_100.gif], and use the residue calculus to compute the value of the integral.

[Graphics:../Images/IntegralsRationalMod_gr_101.gif]





[Graphics:../Images/IntegralsRationalMod_gr_102.gif]

[Graphics:../Images/IntegralsRationalMod_gr_103.gif]

[Graphics:../Images/IntegralsRationalMod_gr_104.gif]

 

 

 

Or, we can use Mathematica's integral table and evaluate the integral.

[Graphics:../Images/IntegralsRationalMod_gr_105.gif]

[Graphics:../Images/IntegralsRationalMod_gr_106.gif]

 

 

However, for this simple integral Mathematica's can find the correct answer without resorting to the PrincipalValue option.

[Graphics:../Images/IntegralsRationalMod_gr_107.gif]





[Graphics:../Images/IntegralsRationalMod_gr_108.gif]

The above answer is correct too.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) 2006 John H. Mathews, Russell W. Howell