Re: notation help: f(x) = (sin x)^(1/3)

• To: mathgroup at smc.vnet.net
• Subject: [mg29968] Re: [mg29947] notation help: f(x) = (sin x)^(1/3)
• From: Andrzej Kozlowski <andrzej at tuins.ac.jp>
• Date: Fri, 20 Jul 2001 03:28:31 -0400 (EDT)
• Sender: owner-wri-mathgroup at wolfram.com

```First of all you do have a syntax error. What you meant was:

Plot[Sin[x]^(1/3), {x, -10, 10}]

But actually this will also not work. The explanation is again: complex
functions or your lack of acquaintance with them. The point is that  x^(1/3)
is not what you think it is when x is a negative real number (it is a
complex number). There are several ways round it. One of them is to load the
<<Miscellaneous`RealOnly`
package. My preferred way is to use:

Plot[Root[#^3-Sin[x]&,1], {x, -10, 10}]

Here Root[#^3-Sin[x]&,1] means the real cube root of Sin[x].

--
Andrzej Kozlowski
Toyama International University
JAPAN

http://platon.c.u-tokyo.ac.jp/andrzej/
http://sigma.tuins.ac.jp/~andrzej/

on 01.7.19 4:57 PM, Tim 9-23 at bendoftimeb at stny.rr.com wrote:

> How do I plot this.  I must not be entering it correctly.  It's the
> plot of the cube root of the Sine function.
>
> Plot[[Sin[x]]^(1/3), {x, -10, 10}] isn't working.  Thanks.
>
> My email address is anti-spammed.  Remove the 2 B's after hitting email reply
> if you want to email me.
>
> Tim 9-23
>
>

```

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