(Examples)
(Examples)
 
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Linear:
 
Linear:
  
<math>\ S_{1} = 2x(t + 3) + x(t - 8)</math>
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An example of an linear function is <math>\ y(t) = 3x(t + 8)</math>
  
<math>\ S_{2} = x(t - t_{0})</math>
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because the result of the 1st method above yields <math>\ 3ax(t + 8) + 3bx(t + 8)</math>
 
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<math>\ S_{1} \rightarrow S_{2} = 2x(t - t_{0} + 3) + x(t - t_{0} - 8)</math>
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+
<math>\ S_{2} \rightarrow S_{1} = 2x(t - t_{0} + 3) + x(t - t_{0} - 8)</math>
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+
 
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Since the results are the same the system is time invariable.
+
  
 +
and the result of the 2nd method above yields <math>\ 3[ax(t + 8) + bx(t + 8)]</math>. Because they yield the same result the system is linear.
  
 
Non-Linear:
 
Non-Linear:
  
<math>\ S_{1} = x(-t + 3) - x(-t - 8)</math>
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An example of a non-linear function is <math>\ y(t) = e^{x(t)} </math>
 
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<math>\ S_{2} = x(t - t_{0})</math>
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+
<math>\ S_{1} \rightarrow S_{2} = x(-t + t_{0} + 3) - x(-t + t_{0} - 8)</math>
+
 
+
<math>\ S_{2} \rightarrow S_{1} = x(-t - t_{0} + 3) - x(-t - t_{0} - 8)</math>
+
  
 +
because the result of the 1st method above yields <math>\ e^{ax(t)} + e^{bx(t)}</math>
  
Since the results are different they system is time variant.
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and the result of the 2nd method above yields <math>\ e^{ax(t) + bx(t)}</math>, which is not equal to the first result.

Latest revision as of 10:22, 12 September 2008

Definition

If Z(t) and W(t) in the following are equal the system is linear.


Linearity Part 1 ECE301Fall2008mboutin.jpg



Linearity Part 2 ECE301Fall2008mboutin.jpg

Examples

Linear:

An example of an linear function is $ \ y(t) = 3x(t + 8) $

because the result of the 1st method above yields $ \ 3ax(t + 8) + 3bx(t + 8) $

and the result of the 2nd method above yields $ \ 3[ax(t + 8) + bx(t + 8)] $. Because they yield the same result the system is linear.

Non-Linear:

An example of a non-linear function is $ \ y(t) = e^{x(t)} $

because the result of the 1st method above yields $ \ e^{ax(t)} + e^{bx(t)} $

and the result of the 2nd method above yields $ \ e^{ax(t) + bx(t)} $, which is not equal to the first result.

Alumni Liaison

Ph.D. 2007, working on developing cool imaging technologies for digital cameras, camera phones, and video surveillance cameras.

Buyue Zhang