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RE: How to find and plot real roots?

  • To: mathgroup at smc.vnet.net
  • Subject: [mg33572] RE: [mg33566] How to find and plot real roots?
  • From: "David Park" <djmp at earthlink.net>
  • Date: Mon, 1 Apr 2002 02:02:04 -0500 (EST)
  • Sender: owner-wri-mathgroup at wolfram.com

Chitchanok,

Use the RealOnly standard package.

Needs["Miscellaneous`RealOnly`"]

(-1)^(1/3)
-1

Plot[x^(1/3)*(3 + x)^(2/3), {x, -2, 2}];

works without any error messages.

The problem with the RealOnly package is that, once you load the package,
you can't turn the feature off without quitting the kernel. Ted Ersek has a
package on MathSource called SwitchableRealOnly that allows you to turn the
real only feature on and off and is somewhat more robust in other ways.

David Park
djmp at earthlink.net
http://home.earthlink.net/~djmp/

> From: Chitchanok Carlen [mailto:anok at earthlink.net]
To: mathgroup at smc.vnet.net
>
>
> How does one find the real root, for example:
>
> (-1)^(1/3) in Mathematica ?
>
> Also, I want to plot x^(1/3)*(x+3)^(2/3), but the fact that
> Mathematica doesn't
> know which roots to pick causes errors in the Plot function.  How
> to force
> it to find real roots?
>
> Thanks.
>



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