Re: How to Integrate[Abs[x]]?

*To*: mathgroup at smc.vnet.net*Subject*: [mg91639] Re: How to Integrate[Abs[x]]?*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sat, 30 Aug 2008 01:52:16 -0400 (EDT)

On 8/29/08 at 4:25 AM, lobais at gmail.com (Thomas Dybdahl Ahle) wrote: >On my Ti calculater |x| is easily integrated to |x|*x/2, but when I >type Integrate[Abs[x],x] in mathematica, it seams like it can't find >the solution. Is there anything I'll have to do, to make mathematica >find the solution? Your TI calculator undoubtedly assumes the domain of x to be real numbers. Mathematica by default assumes the domain of x to be complex numbers. And that is why no solution to the integral is returned. You can restrict x to be a real number by using Assuming. For example, In[2]:= Assuming[x \[Element] Reals, Integrate[Abs[x], x]] Out[2]= Piecewise[{{-(x^2/2), x <= 0}}, x^2/2]