Re: Re: Integrate a Piecewise funition, stange behaviour
- To: mathgroup at smc.vnet.net
- Subject: [mg53870] Re: [mg53851] Re: Integrate a Piecewise funition, stange behaviour
- From: DrBob <drbob at bigfoot.com>
- Date: Tue, 1 Feb 2005 04:08:20 -0500 (EST)
- References: <200501280743.CAA00286@smc.vnet.net> <ctfvgo$pi8$1@smc.vnet.net> <200501300818.DAA08819@smc.vnet.net>
- Reply-to: drbob at bigfoot.com
- Sender: owner-wri-mathgroup at wolfram.com
Both integrals evaluate almost instantly in version 5.1: f=Piecewise[{{2/355,Inequality[ 2,LessEqual,w[2],LessEqual,8]&&Inequality[4,LessEqual,w[2]+w[3], LessEqual,12]&&Inequality[5, LessEqual,w[1]+w[2],LessEqual,10]&&w[1]â?¤0&&w[3]â?¤0}},0]; int1=Integrate[f,{w[2],-Infinity,Infinity}] Piecewise[{{(2/355)*(3 + w[1]), (-3 < w[1] < -2 && w[1] - w[3] < 1 && w[3] <= 0) || (-2 <= w[1] <= 0 && w[1] - w[3] <= 1 && w[3] <= 0)}, {(2/355)*(4 + w[3]), (w[3] > -4 && -3 < w[1] < -2 && w[1] - w[3] >= 1) || (w[3] > -4 && -2 <= w[1] <= 0 && w[1] - w[3] > 1)}}] red1=Reduce[Inequality[ 2,LessEqual,w[2],LessEqual,8]&&Inequality[4,LessEqual,w[ 2]+w[3],LessEqual,12]&&Inequality[5,LessEqual,w[1]+ w[2],LessEqual,10]&&w[1]â?¤0&&w[3]â?¤0]; int2=Integrate[(2/355)*Boole[red1],{w[2],-Infinity,Infinity}] Piecewise[{{6/355, w[1] == 0 && -1 <= w[3] <= 0}, {(2/355)*(3 + w[1]), -3 < w[1] < 0 && w[1] - w[3] < 1 && w[3] <= 0}, {(2/355)*(4 + w[3]), (w[1] == 0 && -4 < w[3] < -1) || (-3 < w[1] < 0 && w[3] > -4 && w[1] - w[3] >= 1)}}] Bobby On Sun, 30 Jan 2005 03:18:12 -0500 (EST), rik <rikypi_CREPA_SPAMMONE at libero.it> wrote: > DrBob ha scritto: >> Try posting in InputForm, so that the code isn't so garbled. >> >> http://www.eclecticdreams.net/DrBob/copy_as_inputform.htm >> >> Bobby >> >> On Fri, 28 Jan 2005 02:43:42 -0500 (EST), rik <rikypi_CREPA_SPAMMONE at libero.it> wrote: >> >> > > > i've followed the instruction, and this's the result. I hope that source > is more readable now. > > f = Piecewise[{{2/355, Inequality[2, LessEqual, w[2], LessEqual, 8] && > Inequality[4, LessEqual, w[2] + w[3], LessEqual, 12] && > Inequality[5, LessEqual, w[1] + w[2], LessEqual, 10] && w[1] <= 0 > && w[3] <= 0}}, 0] > > int1 = Integrate[f, {w[2], -Infinity, Infinity}] > > red1 = Reduce[Inequality[2, LessEqual, w[2], LessEqual, 8] && > Inequality[4, LessEqual, w[2] + w[3], LessEqual, > 12] && Inequality[5, LessEqual, w[1] + w[2], LessEqual, 10] && w[1] > <= 0 && w[3] <= 0] > > int2 = Integrate[(2/355)*Boole[red1], {w[2], -Infinity, Infinity}] > > thanks a lot! > > > > -- DrBob at bigfoot.com www.eclecticdreams.net