Re: Bug in Calculus`DiracDelta`
- To: mathgroup at smc.vnet.net
- Subject: [mg14801] Re: Bug in Calculus`DiracDelta`
- From: "M. Rommel" <rommel at bc.edu>
- Date: Wed, 18 Nov 1998 01:29:01 -0500
- Organization: UltraNet Communications , an RCN Company http://www.ultranet.com/
- References: <72je71$3f9@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Let me add that the correct solution is
Integrate[DiracDelta[Cos[phi]],{phi,Pi,2Pi}]=1
You may take the Cos out of the DiracDelta, then you have
Integrate[DiracDelta[phi -3Pi/2]/Abs[Sin[3Pi/2]],{phi,Pi,2Pi}]=1
Apparently the DiracDelta package fails in that regard
M. Rommel wrote in message <72je71$3f9 at smc.vnet.net>...
>I know normally "it's the user, stupid!" but this one seems real.
>
>In[1]:= <<Calculus`DiracDelta`
>
>In[2]:= Integrate[DiracDelta[Cos[x]],{x,0,\[Pi]}]
>
>Out[2]= 1
>
>That's what I agree with but the next line I cannot:
>
>In[3]:= Integrate[DiracDelta[Cos[x]],{x,\[Pi],2\[Pi]}]
>
>Out[3]= 0
>
>Any comments/insights/etc. pp.?
>
>Cheers, Martin.
>
>