Example 8.15.  Evaluate  [Graphics:Images/IntegralsRationalMod_gr_61.gif].  

[Graphics:Images/IntegralsRationalMod_gr_62.gif]

Explore Solution 8.15.

Enter the function  [Graphics:../Images/IntegralsRationalMod_gr_71.gif]  and locate the singularities.

[Graphics:../Images/IntegralsRationalMod_gr_72.gif]





[Graphics:../Images/IntegralsRationalMod_gr_73.gif]

 

 

 

Determine which poles lie in the upper half plane ?

[Graphics:../Images/IntegralsRationalMod_gr_74.gif]



[Graphics:../Images/IntegralsRationalMod_gr_75.gif]

[Graphics:../Images/IntegralsRationalMod_gr_76.gif]

 

 

 

Compute the residues at  [Graphics:../Images/IntegralsRationalMod_gr_77.gif], and use the residue calculus to compute the value of the integral.

[Graphics:../Images/IntegralsRationalMod_gr_78.gif]





[Graphics:../Images/IntegralsRationalMod_gr_79.gif]

[Graphics:../Images/IntegralsRationalMod_gr_80.gif]

[Graphics:../Images/IntegralsRationalMod_gr_81.gif]

 

 

 

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

[Graphics:../Images/IntegralsRationalMod_gr_82.gif]

[Graphics:../Images/IntegralsRationalMod_gr_83.gif]

 

 

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

[Graphics:../Images/IntegralsRationalMod_gr_84.gif]





[Graphics:../Images/IntegralsRationalMod_gr_85.gif]

The above answer is correct too.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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