Mathematica 9 is now available
Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2007
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2007

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: Dirac Delta Function: Basics

  • To: mathgroup at smc.vnet.net
  • Subject: [mg75215] Re: Dirac Delta Function: Basics
  • From: dh <dh at metrohm.ch>
  • Date: Fri, 20 Apr 2007 00:46:42 -0400 (EDT)
  • References: <f07a53$4ci$1@smc.vnet.net>


Hi Gopinath,

there is a pitfall here. The Fourier sum is by definition a periodic 

function. Therefore, either you restrict your domain to {-Pi,Pi} and 

then you have a Delta function in your domain. Or, if your domain is 

{-Infinity,Infinity} you are using a grid of Delta functions. If you 

want a Delta function in this domain, you need a Fourier integral.

hope this helps, Daniel



Gopinath Venkatesan wrote:

> Hello Friends

> 

> I browsed some of the previous posts in this forum on Dirac Delta function, and found some interesting distributions used to represent the delta function, at the below website:

> 

> <http://mathworld.wolfram.com/DeltaFunction.html>

> 

> Also when I tried using one of the distribution, Fourier series approximation (shown below), I was getting very different solutions for different entries of upper limit of k, even at higher values of upper limits.

> 

> DeltaF(x - a) = 1/(2*Pi) + 

>    (1/Pi)*Sum[Cos[k*a]*Cos[k*x] + Sin[k*a]*Sin[k*x], 

>      {k, 1, Infinity}]

> 

> (here DeltaF is DiracDelta).

> 

> Does anyone here can give me suggestions on using right distributions and parameters. Thanks.

> 

> Also Can I use the DiracDelta[] function available in Mathematica itself. How does Mathematica calculate them.

> 

> I am not integrating the equation containing DiracDelta[], so as seen from the Mathematica examples, I think it is doing Laplace transformations.

> 

> Any help/directions to resources are appreciated. Thanks,

> 

> Gopinath

> Graduate Student

> University of Oklahoma

> 




  • Prev by Date: Re: Complex bessel function
  • Next by Date: Re: Help in analytical integration 3
  • Previous by thread: Re: Dirac Delta Function: Basics
  • Next by thread: Re: Dirac Delta Function: Basics