Re: Re: (x-y) DiracDelta[x-y] does not simplify to 0
- To: mathgroup at smc.vnet.net
- Subject: [mg56376] Re: [mg56297] Re: (x-y) DiracDelta[x-y] does not simplify to 0
- From: Alain Cochard <alain at geophysik.uni-muenchen.de>
- Date: Sat, 23 Apr 2005 01:16:08 -0400 (EDT)
- References: <4FDA877403669E48A2CB7F1122A7948045C78F@dassne02.da.gei>
- Reply-to: alain at geophysik.uni-muenchen.de
- Sender: owner-wri-mathgroup at wolfram.com
Wolf, Hartmut writes:
> In[14]:= f[x_,y_] := (1 + x + y + x^2)/(x - y)
>
> In[15]:= Integrate[f[x,y]*(x - y)DiracDelta[x - y], {x, -Infinity,
> Infinity}]
> Out[15]= (1 + y)^2
OK, with this example I realize that Andrzej and Yehuda were probably
correct from the start, since with my simplification outside the
integral, and if not too careful, I might have deduced that this would
give 0.
Thanks again everybody,
Alain