(Examples)
 
Line 20: Line 20:
 
</pre>
 
</pre>
 
Therefore, this system is linear
 
Therefore, this system is linear
 +
 +
 +
A Non-linear System:
 +
 +
<math> y(t) = x(t)^2 </math>
 +
 +
<pre>
 +
x1(t) -> Ax1(t)
 +
                |+|  Ax(t) + Bx(t) -System-> (Ax(t) + Bx(t))^2
 +
x2(t) -> Bx2(t)
 +
 +
x1(t) -System-> x1(t)^2 -> Ax1(t)^2
 +
                                    |+|  Ax1(t)^2 + Bx2(t)^2
 +
x2(t) -System-> x2(t)^2 -> Bx2(t)^2
 +
</pre>
 +
 +
Therefore, this system is non-linear

Latest revision as of 12:14, 11 September 2008

A system is called linear if:

Linearity ECE301Fall2008mboutin.png


Examples

A Linear System:

$ y(t) = 2x(2t) $

x1(t) -> Ax1(t)
                |+|  Ax(t) + Bx(t) -System-> 2Ax1(2t) + 2Bx2(2t) 
x2(t) -> Bx2(t)

x1(t) -System-> 2x1(2t) -> 2Ax1(2t)
                                    |+|  2Ax1(2t) + 2Bx2(2t)
x2(t) -System-> 2x2(2t) -> 2Bx2(2t) 

Therefore, this system is linear


A Non-linear System:

$ y(t) = x(t)^2 $

x1(t) -> Ax1(t)
                |+|  Ax(t) + Bx(t) -System-> (Ax(t) + Bx(t))^2 
x2(t) -> Bx2(t)

x1(t) -System-> x1(t)^2 -> Ax1(t)^2
                                    |+|  Ax1(t)^2 + Bx2(t)^2
x2(t) -System-> x2(t)^2 -> Bx2(t)^2 

Therefore, this system is non-linear

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