Re: Modulus / Absolute Value

*To*: mathgroup at smc.vnet.net*Subject*: [mg90080] Re: [mg90058] Modulus / Absolute Value*From*: Murray Eisenberg <murray at math.umass.edu>*Date*: Sat, 28 Jun 2008 05:52:15 -0400 (EDT)*Organization*: Mathematics & Statistics, Univ. of Mass./Amherst*References*: <200806271019.GAA24305@smc.vnet.net>*Reply-to*: murray at math.umass.edu

What problem are you actually trying to solve? (You do not say!) Why are you using awkward LaTeX mark-up here? (Since you have a Mathematica question, why not start with Mathematica notation? Type it into a Mathematica notebook, then use Edit > Copy As > Plain Text to copy it into your e-mail message.) What does the function g have to do with this? (I don't see its relevance at all; I think your question is really about integrating f, isn't it?) Possibly the question you are asking is, in effect, how to find the total area enclosed between the graph of f[x_] := Sin[2x] and the x-axis over the interval from 0 to Pi. This is simply: Integrate[ Abs[f[x]], {x, 0, Pi} ] Perhaps you wanted to add to that the area enclosed by the graph of g and the x-axis, over that same interval. You could add to the preceding the value of Integrate[ Abs[g[x]], {x, 0, Pi} ] or, since g[x]<= 0 when 0 <=x <= Pi, simply add - Integrate[g[x], {x, 0, Pi} ] Felipe Mannshardt wrote: > Greetings, > > i have been searching the way to tell Mathematica to use Modulus / Absolute Value. I have been unable to find. > > LATEX > \left(\int_0^{\frac{\pi }{2}} f[x] \, dx+\int_{\frac{\pi }{2}}^{\pi } f[x] \, dx\right)+\int_0^{\pi } g[x] \, dx > /LATEX > I should be subtracting the upper Integral from the lower Integral, > but since i could not find a way to tell Mathematica to use Modulus /Absolute Value. I had to add the upper to the lower . . . > > my functions are, f and g > > LATEX > f[\text{x$\_$}]\text{:=}\text{Sin}[2*x]g[\text{x$\_$}]\text{:=}x^2-(\pi *x) > /LATEX > So, can some1 help me out with this one? How to use Modulus/Absolute Value (German, Betrag) with Mathematica. > > -- Murray Eisenberg murray at math.umass.edu Mathematics & Statistics Dept. Lederle Graduate Research Tower phone 413 549-1020 (H) University of Massachusetts 413 545-2859 (W) 710 North Pleasant Street fax 413 545-1801 Amherst, MA 01003-9305

**References**:**Modulus / Absolute Value***From:*Felipe Mannshardt <vexie.infamous@googlemail.com>