Re: New user question
- To: mathgroup at smc.vnet.net
- Subject: [mg20394] Re: [mg20383] New user question
- From: BobHanlon at aol.com
- Date: Tue, 26 Oct 1999 00:32:50 -0400
- Sender: owner-wri-mathgroup at wolfram.com
Solve[y^3 == -4, y] // N
{{y -> 0.7937005259840992 - 1.3747296369986026*I},
{y -> -1.5874010519681991},
{y -> 0.7937005259840998 + 1.3747296369986022*I}}
For a negative argument, the default cube root is complex
N[(-4)^(1/3)]
0.7937005259840998 + 1.3747296369986022*I
Since you are only interested in the real root
Plot[Sign[x] * Abs[x^(1/3)], {x, -5, 5}];
Bob Hanlon
In a message dated 10/18/1999 5:28:30 AM, moriarty at umd5.umd.edu writes:
>I have just begun to use/learn Mathematica. One of the first things I
>tried was to Plot[x^(1/3),{x,-5,5}] and got error messages indicating that
>the negatives^(1/3) were not machine level real numbers (or close to
>that) - the positive side displayed ok.
>