Dirac delta function

  • Thread starter athrun200
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  • #1
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Homework Statement



attachment.php?attachmentid=37434&stc=1&d=1311345723.jpg


Homework Equations





The Attempt at a Solution



Can I write, say, [itex]f(x) \delta(x)=f(2)\delta(x)[/itex]?
Since [itex]\delta(x)[/itex] =0 for x[itex]\neq[/itex]0
 

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Answers and Replies

  • #2
hunt_mat
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I think you can say [itex]f(x)\delta (x-2)=f(2)\delta (x)[/itex]
 
  • #3
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I think you can say [itex]f(x)\delta (x-2)=f(2)\delta (x)[/itex]

Then if x=2, left hand side will become infinity and the right hand side 0.
Is it Ok?
 
  • #4
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So what's wrong with my post in #1?
 
  • #5
Dick
Science Advisor
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So what's wrong with my post in #1?

The integral of [itex]f(x) \delta(x)[/itex] over x is f(0). The integral of [itex]f(2) \delta(x)[/itex] over x is f(2). So no, they aren't the same.
 

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