Re: a couple of gripes
- To: mathgroup at smc.vnet.net
- Subject: [mg29773] Re: a couple of gripes
- From: "Allan Hayes" <hay at haystack.demon.co.uk>
- Date: Sun, 8 Jul 2001 01:00:17 -0400 (EDT)
- References: <9i6aan$okh$1@smc.vnet.net>
- Sender: owner-wri-mathgroup at wolfram.com
Joshua, Re the first example: we do have Integrate[f[x]*DiracDelta[x-y],{x,-Infinity,Infinity}] f[y] Re the second example: problems are likely if the formal variable x is also used for the mean. A normal distribution with zero standard deviation zero seems also to be related to DiracDelta function. Allan --------------------- Allan Hayes Mathematica Training and Consulting Leicester UK www.haystack.demon.co.uk hay at haystack.demon.co.uk Voice: +44 (0)116 271 4198 Fax: +44 (0)870 164 0565 "Joshua A. Solomon" <J.A.Solomon at city.ac.uk> wrote in message news:9i6aan$okh$1 at smc.vnet.net... > When I evaluate > Integrate[f[x]*If[x==y,1,0],{x,-Infinity,Infinity}] > I don't get > f[y]. > > When I evaluate > PDF[NormalDistribution[x,0],x] > I don't get > 1. > > js > -- > Joshua A. Solomon > Department of Optometry and Visual Science > City University > London EC1V 0HB > Voice: (44) 20 7040 0192 > Secretary/Fax: (44) 20 7040 0182 > J.A.Solomon at city.ac.uk > http://www.staff.city.ac.uk/~solomon > >