Re: Plot Question
- To: mathgroup at smc.vnet.net
- Subject: [mg6839] Re: [mg6797] Plot Question
- From: Allan Hayes <hay at haystack.demon.co.uk>
- Date: Tue, 22 Apr 1997 02:33:16 -0400 (EDT)
- Sender: owner-wri-mathgroup at wolfram.com
"Ivan G. Burch II" <ivanb at hula.net>
[mg6797] Plot Question
>I want to have MMA plot the following:
>
>Plot[{-x^3, -x^(1/3), x}, {x, -10, 10}]
>I get the following errors for this:
>Plot::plnr : -x^(1/3) is not a machine-size number at x = -10
>" " " " " " " " " " " x = -9.18866
>" " " " " " " " " " " x = -8.30382
Ivan:
(-10.0)^(1/3)
1.07722 + 1.8658 I
This is the default complex value (perfectly correct mathematics).
To get the real values (with Mma 3.0) use
<<Miscellaneous`RealOnly`
Now we get
(-10.0)^(1/3)
-2.15443
and your plot will be as you want
Plot[{-x^3, -x^(1/3), x}, {x, -10, 10}]
Allan Hayes
hay at haystack.demon.co.uk
http://www.haystack.demon.co.uk