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