23 Ordinary Differential equations[1QB]
To solve the following exercises, it is imporant to know some fundamental results, such as: the existence and uniqueness theorem 1 , Gronwall’s Lemma; and in general some methods to analyze, solve and qualitative study Ordinary Differential Equations (abbreviated ODE). These may be found e.g. in [ 29 , 24 , 3 ] .
23.1 Autonomous problems
23.2 Resolution
23.3 Qualitative discussions
[ [1R6]]
For the following exercises the following simple comparison lemma may be useful.
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1
2
23.4 Envelope
Given a family of planar curves, we want to define the envelope curve. Let’s see two possible definitions.
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Curve Envelope
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[ [1RT]]
We want to see that the two previous definitions are equivalent in this sense.
23.5 Linear equations (with constant coefficients)
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23.6 Matrix equations
To solve the following exercises you need to know the elementary properties of the exponential of matrices, see section [2D8].