Example 10.12.  The transformation  [Graphics:Images/MapTrigonometricFunMod_gr_1.gif]  is a one-to-one conformal mapping of the vertical strip  [Graphics:Images/MapTrigonometricFunMod_gr_2.gif]  onto the disk  [Graphics:Images/MapTrigonometricFunMod_gr_3.gif].  

Figure 10.16  The composite transformation  [Graphics:Images/MapTrigonometricFunMod_gr_16.gif].

Explore Solution 10.12.

Enter the function  f(z) = tan(z).  

[Graphics:../Images/MapTrigonometricFunMod_gr_17.gif]


[Graphics:../Images/MapTrigonometricFunMod_gr_18.gif]

 

 

Using the trigonometric identities

 

[Graphics:../Images/MapTrigonometricFunMod_gr_19.gif]

We obtain the following form for  f(z) = tan(z).  

[Graphics:../Images/MapTrigonometricFunMod_gr_20.gif]


[Graphics:../Images/MapTrigonometricFunMod_gr_21.gif]

 

 

Which is the same as the following function  [Graphics:../Images/MapTrigonometricFunMod_gr_22.gif].  

[Graphics:../Images/MapTrigonometricFunMod_gr_23.gif]


[Graphics:../Images/MapTrigonometricFunMod_gr_24.gif]

 

 

The first function in this composition is  [Graphics:../Images/MapTrigonometricFunMod_gr_25.gif],  and the second function is a bilinear transformation [Graphics:../Images/MapTrigonometricFunMod_gr_26.gif],  and then  [Graphics:../Images/MapTrigonometricFunMod_gr_27.gif].

[Graphics:../Images/MapTrigonometricFunMod_gr_28.gif]


[Graphics:../Images/MapTrigonometricFunMod_gr_29.gif]

 

 

The image is traced using a graph.

[Graphics:../Images/MapTrigonometricFunMod_gr_30.gif]





[Graphics:../Images/MapTrigonometricFunMod_gr_31.gif]

[Graphics:../Images/MapTrigonometricFunMod_gr_32.gif]

[Graphics:../Images/MapTrigonometricFunMod_gr_33.gif]

[Graphics:../Images/MapTrigonometricFunMod_gr_34.gif]

[Graphics:../Images/MapTrigonometricFunMod_gr_35.gif]

[Graphics:../Images/MapTrigonometricFunMod_gr_36.gif]

We see that the transformation  w = tan(z)  maps the vertical strip  [Graphics:../Images/MapTrigonometricFunMod_gr_37.gif]  onto the disk  [Graphics:../Images/MapTrigonometricFunMod_gr_38.gif].  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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