Re: ..Integrate[Abs[x]... UnitStep again!
- To: mathgroup at smc.vnet.net
- Subject: [mg23728] Re: [mg23712] ..Integrate[Abs[x]... UnitStep again!
- From: "Mark Harder" <harderm at ucs.orst.edu>
- Date: Mon, 5 Jun 2000 01:09:20 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
Jose; It occured to me that Abs[x]= Integrate[Sign[x],x]; but when I tried that, Mathematica generated an "invalid integration limit or variable..." error, so I split the function in two parts joining at x=0 using the Unit Step function & that worked: mySign = UnitStep[t] - UnitStep[-t]; Plot[dublStep, {t, -2, 2} ] (* output omitted *) In>> myAbs = Integrate[mySign, t] Plot[myAbs, {t, -3, 3}] Out>> -t + 2 t UnitStep[t] (* Plot omitted *) In[10]:= Integrate[myAbs, t] Plot[%, {t, -4, 4}] Out[10]= -t^2/2 + t^2 UnitStep[t] (* Plot omitted *) -mark harder harderm at ucs.orst.edu -----Original Message----- From: José María Lasso <jml at accessinter.net> To: mathgroup at smc.vnet.net Subject: [mg23728] [mg23712] Thx for your help >Hi, >Thx for the answers to my last post, but I have a new question, similar to >the last one, when I try: Integrate[Abs[x],x], there is no result, just the >original input, what I am doing wrong?, I need some advice about a good >book about Mathematica for beginers.Thx again.Best regards > >Jose M Lasso > > >