Re: newbie problem with NIntegrate

*To*: mathgroup at smc.vnet.net*Subject*: [mg49804] Re: [mg49791] newbie problem with NIntegrate*From*: Bob Hanlon <hanlonr at cox.net>*Date*: Sun, 1 Aug 2004 18:48:36 -0400 (EDT)*Reply-to*: hanlonr at cox.net*Sender*: owner-wri-mathgroup at wolfram.com

Needs["Calculus`Integration`"]; Geom = 200 >= x >= 100 && 50 >= y >= -50 && -20 <= z <= 20; Table[Integrate[2*Boole[Geom],{ x,0,xmax},{y,-100,100},{z,-30,30}], {xmax,300,900,300}] {800000, 800000, 800000} Bob Hanlon > > From: "Xiaoxun" <dbjunxiao at hotmail.com> To: mathgroup at smc.vnet.net > Date: 2004/08/01 Sun AM 04:09:54 EDT > To: mathgroup at smc.vnet.net > Subject: [mg49804] [mg49791] newbie problem with NIntegrate > > Hi, all, > > Please advices: > > Geom = (200 >=x>= 100 && 50 >= y >= -50 && -20 <= z <= 20); > gr[x_, y_, z_] := 2 /; Geom; > gr[x_, y_, z_] := 0 /; ! (Geom); > N[Integrate[gr[x, y, z], {x, 0, 300}, {y, -100, 100}, {z, -30, 30}] > This gives a result of 799995. > However, if changing the x range to {x,0,600} results 799993. > and {x,0,900} results 0; > > So what could we do to ensure the right answer? >