Re: DiracDelta Function question
- To: mathgroup at smc.vnet.net
- Subject: [mg21329] Re: DiracDelta Function question
- From: "Gregor" <governey at duckman.sid.hp.com>
- Date: Fri, 24 Dec 1999 03:42:31 -0500 (EST)
- Organization: SSO-IT, Hewlett-Packard Co.
- References: <831vk0$g89@smc.vnet.net> <83aare$qq0@smc.vnet.net> <83ncod$6ed$3@dragonfly.wolfram.com>
- Sender: owner-wri-mathgroup at wolfram.com
It appears to be a bug with Mathematica 4 on NT4 SP6a. It should calculate also the
first input. Both are 1/2 (at least using a pencil and paper).
In[8]:=
Integrate[DiracDelta[2 x - 1], {x, -Infinity, +Infinity}]
Out[8]=
\!\(\*
RowBox[{
SubsuperscriptBox["\[Integral]",
InterpretationBox[\(-\[Infinity]\),
DirectedInfinity[ -1]],
InterpretationBox["\[Infinity]",
ectedInfinity[
1]]], \(DiracDelta[\(-1\) + 2\ x] \[DifferentialD]x\)}]\)
In[4]:=
Integrate[DiracDelta[2 x - 2], {x, -Infinity, +Infinity}]
Out[4]=
\!\(1\/2\)
John M. Jowett wrote in message <83ncod$6ed$3 at dragonfly.wolfram.com>...
>
>
>Bojan Bistrovic wrote:
>>
>> Julian Francis wrote:
>> > Why is mathematica unable to evaluate:
>> > Integrate[DiracDelta[2 x - 1], {x, -Infinity, +Infinity}]
>> >
>> > Also interestingly:
>> > Integrate[DiracDelta[2 x - 2], {x, -Infinity, +Infinity}]
>> >
>> > returns (1/2)
>> >
>> > I should have thought that the answer in both cases would be 1.
>>>>>>>>>> SNIP <<<<<<<<<<<<<
>> It's probably a bug in MS-Windows :-). My Linux version returns 1/2 in
>
>On my Windows (NT) system, Mathematica 4.0 returns 1/2, quite correctly,
>for both cases. (The first one may have taken a few seconds longer
>while Mathematica loaded something behind the scenes.)
>
>John Jowett
>
>
>