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Re: Different answers in mathematica and my calculator.

  • To: mathgroup at smc.vnet.net
  • Subject: [mg125616] Re: Different answers in mathematica and my calculator.
  • From: Murray Eisenberg <murray at math.umass.edu>
  • Date: Thu, 22 Mar 2012 05:48:42 -0500 (EST)
  • Delivered-to: l-mathgroup@mail-archive0.wolfram.com
  • References: <201203211047.FAA27137@smc.vnet.net>
  • Reply-to: murray at math.umass.edu

Informally, you're correct. But technically, you're not. After all, a 
real number _is_ complex. (One shouldn't confuse "non-real complex" with 
"complex.)

On 3/21/12 6:47 AM, DrMajorBob wrote:
> -1 is a real cube root of -1, so it's not quite correct to say "(-1)^(1/3)
> is complex".
>
> Two cube roots of -1 ARE complex, of course.
>
> Bobby
>
> On Tue, 20 Mar 2012 02:21:56 -0500, psycho_dad<s.nesseris at gmail.com>
> wrote:
>
>> I'm afraid that Sec corresponds to 1/Cos in the sense of 2 and 1/2
>> respectively. The function you want is ArcCos (inverse cosine).
>>
>> As for the first question, mathematica is right, so you are either doing
>> something wrong on the calculator or it doesn't support complex numbers,
>> as Power[2(-2)+3, (3)^-1]=(-1)^(1/3) is complex.
>>
>
>

-- 
Murray Eisenberg                     murray at math.umass.edu
Mathematics & Statistics Dept.
Lederle Graduate Research Tower      phone 413 549-1020 (H)
University of Massachusetts                413 545-2859 (W)
710 North Pleasant Street            fax   413 545-1801
Amherst, MA 01003-9305



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