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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
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