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Re: Re: The graph of (x + 2)^(1/5) + 4 not plotted

  • To: mathgroup at smc.vnet.net
  • Subject: [mg103966] Re: [mg103962] Re: The graph of (x + 2)^(1/5) + 4 not plotted
  • From: victor chg <kindlychung at gmail.com>
  • Date: Wed, 14 Oct 2009 07:54:38 -0400 (EDT)
  • References: <868306d90910120643u7f1c2299v2cd1845508dc85b7@mail.gmail.com>

This works, only the axes are not at normal positions, looks a bit strange:
http://i38.tinypic.com/20f6ftg.png


On Wed, Oct 14, 2009 at 11:22 AM, Mike Bryniarski <melondisco at gmail.com>wrote:

> The link you posted does not seem to relate to your problem. you
> wanted to show :
>
> Plot[ (x + 2)^(1/5) + 4 , {x, -4, 4}]
>
> I tried plotting the function in your subject and not surprisingly it
> did not plot correctly.
> the issue is taking the fifth root of x on Mathematica can result in a
> complex number. (This can bee seen under possible issues on the Power
> page in the documentation)
> Example:
>
> in: (x + 2)^(1/5) + 4 /. x -> -3
>
> out: 4 + (-1)^(1/5)
>
> The most obvious way (at least for me) to overcome this is to perform
> some algebra on the function to eliminate the fractional power and
> plot it in ContourPlot instead:
>
> ContourPlot[(y - 4)^5 == x + 2, {x, -4, 4}, {y, 0, 6}]
>
> This is the result I assume you were looking for.
>
> On Oct 13, 7:22 am, victor chg <kindlych... at gmail.com> wrote:
> > Here is the link to the image:http://tinypic.com/view.php?pic=veae6u&s=
> =4 <http://tinypic.com/view.php?pic=veae6u&s=%0A=4>
> >
> > Victor Chg
> > --------------------------------------
> > Neuroscience Research Institute, Peking University, Beijing, P.R.China
> > 100038
>
>
>


-- 
--------------------------------------
Neuroscience Research Institute, Peking University, Beijing, P.R.China
100038



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