(Basics of Linearity)
(Basics of Linearity)
Line 14: Line 14:
 
<math>\ \dfrac{t e^{-2 i x} + t e^{2 i x}}{2} </math>
 
<math>\ \dfrac{t e^{-2 i x} + t e^{2 i x}}{2} </math>
 
but
 
but
:<math>e^{2 x i}=\cos 2x + i \sin 2x \, </math> and <math>e^{-2 x i}=\cos 2x - i \sin 2x \, </math> so the response is
+
:<math>e^{2 x i}=\cos 2x + i \sin 2x \, </math> and  
 +
:<math>e^{-2 x i}=\cos 2x - i \sin 2x \, </math>  
 +
:so the response is equal to
  
:<math>\dfrac{t e^{-2 i x} + t e^{2 i x}}{2} = t\cos 2t </math>
+
:<math>\cos 2t </math>

Revision as of 07:34, 18 September 2008

Basics of Linearity

Given

$ e^{2 x i}=t e^{-2 x i}\, $
$ e^{-2 x i}=t e^{2 x i}\, $
The Signal is Linear


$ \cos x = \dfrac{e^{i x}+e^{-i x}}{2} $
$ \cos 2x = \dfrac{e^{2 i x}+e^{-2 i x}}{2} $

The Systems response to $ \cos 2x $ is $ \ \dfrac{t e^{-2 i x} + t e^{2 i x}}{2} $ but

$ e^{2 x i}=\cos 2x + i \sin 2x \, $ and
$ e^{-2 x i}=\cos 2x - i \sin 2x \, $
so the response is equal to
$ \cos 2t $

Alumni Liaison

Basic linear algebra uncovers and clarifies very important geometry and algebra.

Dr. Paul Garrett