Line 3: Line 3:
 
A system is called linear if and only if:
 
A system is called linear if and only if:
  
<math>f(ax_1 + bx_2) = af(x_1) + bf(x_2)</math>
+
<math>f(ax_1 + bx_2) = af(x_1) + bf(x_2)\,</math>
  
 
== Example of a linear system ==
 
== Example of a linear system ==
Line 15: Line 15:
 
<math>f(aX_1 + bX_2) = af(X_1) + bf(X_2) \,</math>
 
<math>f(aX_1 + bX_2) = af(X_1) + bf(X_2) \,</math>
  
<math>f(at^2 + 2bt^2) = af(t^2) + bf(t^2) \,</math>
+
<math>f(at^2 + 2bt^2) = af(t^2) + bf(2t^2) \,</math>
  
 
<math>f(at^2 + 2bt^2) = a*23t^2 + b*46t^2 \,</math>
 
<math>f(at^2 + 2bt^2) = a*23t^2 + b*46t^2 \,</math>
Line 28: Line 28:
  
 
== Example of a non-linear system ==
 
== Example of a non-linear system ==
System is: <math> f(x) = 23x + 1<math>
+
System is: <math> f(x) = 23x + 1\,<math>
 
<math>X_1(t) = t^2 \,</math>
 
<math>X_1(t) = t^2 \,</math>
  
Line 34: Line 34:
  
  
<math>f(aX_1 + bX_2) = af(X_1) + bf(X_2) </math>
+
<math>f(aX_1 + bX_2) \neq af(X_1) + bf(X_2) \,</math>
  
<math>f(at^2 + 2bt^2) = af(t^2) + bf(t^2) </math>
+
<math>f(at^2 + 2bt^2) \neq af(t^2) + bf(2t^2) \,</math>
  
<math>f(at^2 + 2bt^2) = a*23t^2 + b*46t^2 \,</math>
+
<math>f(at^2 + 2bt^2) \neq a(23t^2+1) + b(23*(2t^2)+1) \,</math>
  
<math>f(at^2 + 2bt^2) = 23(at^2 + 2bt^2) \,</math>
+
<math>f(at^2 + 2bt^2) \neq 23 at^2 + 1 + 46 bt^2 + b \,</math>
  
<math> f(x) = 23x \,</math>
+
<math> f(at^2 + 2bt^2) \neq 23 (at^2 + 2bt^2) + a + b \,</math>
 +
 
 +
<math> f(aX_1 + bX_2) \neq af(X_1) + bf(X_2) \,</math>

Revision as of 17:27, 10 September 2008

Linearity

A system is called linear if and only if:

$ f(ax_1 + bx_2) = af(x_1) + bf(x_2)\, $

Example of a linear system

System is: $ f(x) = 23x \, $

$ X_1(t) = t^2 \, $

$ X_2(t) = 2t^2 \, $


$ f(aX_1 + bX_2) = af(X_1) + bf(X_2) \, $

$ f(at^2 + 2bt^2) = af(t^2) + bf(2t^2) \, $

$ f(at^2 + 2bt^2) = a*23t^2 + b*46t^2 \, $

$ f(at^2 + 2bt^2) = 23(at^2 + 2bt^2) \, $

$ f(x) = 23x \, $



Example of a non-linear system

System is: $ f(x) = 23x + 1\,<math> <math>X_1(t) = t^2 \, $

$ X_2(t) = 2t^2 \, $


$ f(aX_1 + bX_2) \neq af(X_1) + bf(X_2) \, $

$ f(at^2 + 2bt^2) \neq af(t^2) + bf(2t^2) \, $

$ f(at^2 + 2bt^2) \neq a(23t^2+1) + b(23*(2t^2)+1) \, $

$ f(at^2 + 2bt^2) \neq 23 at^2 + 1 + 46 bt^2 + b \, $

$ f(at^2 + 2bt^2) \neq 23 (at^2 + 2bt^2) + a + b \, $

$ f(aX_1 + bX_2) \neq af(X_1) + bf(X_2) \, $

Alumni Liaison

Prof. Math. Ohio State and Associate Dean
Outstanding Alumnus Purdue Math 2008

Jeff McNeal