Example 11.  Plot the solutions to the D. E.  [Graphics:Images/HarvestingModelMod_gr_200.gif]  in Example 9
that have the following initial conditions  [Graphics:Images/HarvestingModelMod_gr_201.gif].

Solution 11.

We could try the above technique where we solve  [Graphics:../Images/HarvestingModelMod_gr_202.gif]  for  [Graphics:../Images/HarvestingModelMod_gr_203.gif].
But it will involve complex numbers.  Hang in there !

[Graphics:../Images/HarvestingModelMod_gr_204.gif]

[Graphics:../Images/HarvestingModelMod_gr_205.gif]

Notice that there are multiple solutions for some of these values.
Special care and attention must be given to locate the ones to use, they are:
[Graphics:../Images/HarvestingModelMod_gr_206.gif]
Now replace these constants.

[Graphics:../Images/HarvestingModelMod_gr_207.gif]

[Graphics:../Images/HarvestingModelMod_gr_208.gif]

Make them look nicer.  

[Graphics:../Images/HarvestingModelMod_gr_209.gif]

[Graphics:../Images/HarvestingModelMod_gr_210.gif]

It might be better to just solve the D.E. with the required initial conditions.

[Graphics:../Images/HarvestingModelMod_gr_211.gif]

[Graphics:../Images/HarvestingModelMod_gr_212.gif]

Then form the construction with the following two steps.

[Graphics:../Images/HarvestingModelMod_gr_213.gif]

[Graphics:../Images/HarvestingModelMod_gr_214.gif]

[Graphics:../Images/HarvestingModelMod_gr_215.gif]

[Graphics:../Images/HarvestingModelMod_gr_216.gif]

This is the same list that was obtained using those pesky complex numbers.

Graph these solutions.

[Graphics:../Images/HarvestingModelMod_gr_217.gif]


[Graphics:../Images/HarvestingModelMod_gr_218.gif]

[Graphics:../Images/HarvestingModelMod_gr_219.gif]

 

Observe.  The family of functions [Graphics:../Images/HarvestingModelMod_gr_220.gif]
tend to the constant function  [Graphics:../Images/HarvestingModelMod_gr_221.gif]  as  [Graphics:../Images/HarvestingModelMod_gr_222.gif].  

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

(c) John H. Mathews 2004