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Re: question related to (-1)^(1/3)

  • To: mathgroup at smc.vnet.net
  • Subject: [mg96749] Re: question related to (-1)^(1/3)
  • From: "Sjoerd C. de Vries" <sjoerd.c.devries at gmail.com>
  • Date: Mon, 23 Feb 2009 05:04:56 -0500 (EST)
  • References: <gnqo3c$c95$1@smc.vnet.net>

This misunderstanding pops up over and over again in this group.
Please type tutorial/FunctionsThatDoNotHaveUniqueValues in the search
bar of the mathematica doc centre.

Cheers -- Sjoerd

On Feb 22, 7:33 am, "=D2=BB=D2=B6=D6=AA=C7=EF" <lxguard... at yahoo.com.cn> =
wrote:
> I have tried expression:
> RecurrenceTable[{x[n + 1] == -x[n]^(1/3), x[0] == 1},
>   x, {n, 1, 200}] // N
>
> Mathematica produce
>  {-1., -0.5 - 0.866025 I, -0.766044 + 0.642788 I, -0.686242 -
>   0.727374 I, -0.71393 + 0.700217 I, -0.704818 - 0.709389 I,
> ...
>
> But it should be {1, -1, 1, -1, ... }
>
> If you try  (-1)^(1/3)
>
> In[10]:= (-1)^(1/3)
>
> Out[10]= (-1)^(1/3)
>
> In[11]:= % // N
>
> Out[11]= 0.5 + 0.866025 I



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