Example
8.18. Evaluate
.
![[Graphics:Images/IntegralsTrigImproperMod_gr_51.gif]](../Images/IntegralsTrigImproperMod_gr_51.gif)
Explore Solution 8.18.
Enter the functions
and
and
locate the singularities of f[z].
![[Graphics:../Images/IntegralsTrigImproperMod_gr_61.gif]](../Images/IntegralsTrigImproperMod_gr_61.gif)
Which poles lie in the upper half plane?
![[Graphics:../Images/IntegralsTrigImproperMod_gr_63.gif]](../Images/IntegralsTrigImproperMod_gr_63.gif)
![[Graphics:../Images/IntegralsTrigImproperMod_gr_64.gif]](../Images/IntegralsTrigImproperMod_gr_64.gif)
Compute the residues at
, and
use the residue calculus to compute the value of the integral.
![[Graphics:../Images/IntegralsTrigImproperMod_gr_67.gif]](../Images/IntegralsTrigImproperMod_gr_67.gif)
![[Graphics:../Images/IntegralsTrigImproperMod_gr_68.gif]](../Images/IntegralsTrigImproperMod_gr_68.gif)
![[Graphics:../Images/IntegralsTrigImproperMod_gr_69.gif]](../Images/IntegralsTrigImproperMod_gr_69.gif)
Remark. The integral of F[x] for this problem is g[x], but it cannot be used in any meaningful way to solve the problem at hand.
![[Graphics:../Images/IntegralsTrigImproperMod_gr_71.gif]](../Images/IntegralsTrigImproperMod_gr_71.gif)
This looks good, however it cannot be used to solve for the definite integral. This does not agree with the answer obtained with the residue calculus.
![]()
However, the definite integral will produce the following result.
![]()
Which is also the correct answer.
The PrincipalValue option can also be used.
![]()