Re: DiracDelta Function question
- To: mathgroup at smc.vnet.net
- Subject: [mg21195] Re: DiracDelta Function question
- From: "Bill Bertram" <wkb at ansto.gov.au>
- Date: Fri, 17 Dec 1999 01:24:24 -0500 (EST)
- Organization: Australian Nuclear Science and Technology Organisation
- References: <831vk0$g89@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Julian Francis wrote in message <831vk0$g89 at smc.vnet.net>...
>Folks,
>
>Why is mathematica unable to evaluate:
>Integrate[DiracDelta[2 x - 1], {x, -Infinity, +Infinity}]
I don't know. However,
>Integrate[DiracDelta[2 x - 2], {x, -Infinity, +Infinity}]
>
>returns (1/2)
>
>I should have thought that the answer in both cases would be 1.
No, the Mathematica result is correct! To see why, change the integration
variable to
z = 2x, the integral then becomes (1/2) Integrate[DiracDelta[z -
2],{z,-Infinity,Infinity}].
Cheers,
Bill