Services & Resources / Wolfram Forums
-----
 /
MathGroup Archive
2000
*January
*February
*March
*April
*May
*June
*July
*August
*September
*October
*November
*December
*Archive Index
*Ask about this page
*Print this page
*Give us feedback
*Sign up for the Wolfram Insider

MathGroup Archive 2000

[Date Index] [Thread Index] [Author Index]

Search the Archive

Re: a question about complex variable

  • To: mathgroup at smc.vnet.net
  • Subject: [mg21646] Re: a question about complex variable
  • From: Jens-Peer Kuska <kuska at informatik.uni-leipzig.de>
  • Date: Fri, 21 Jan 2000 03:59:56 -0500 (EST)
  • Organization: Universitaet Leipzig
  • References: <200001170343.WAA13446@smc.vnet.net> <8615hh$jtk@smc.vnet.net>
  • Sender: owner-wri-mathgroup at wolfram.com

ZHU Xiaopeng wrote:
> 
> In my algebra computation, I obtain a expression:
> C = (- I Cos[2 P] - Sin[2 P]) Tan[A]
> P,A are real variables. Apperently, the argument of C is -2(P+Pi/4) and the
> absolute value of C is Tan[A]. But when I use Arg[C] and Abs[C], Mathematica
> tells me:
> 
> Out[41]=Abs[(-I Cos[2 P] - Sin[2 P]) Tan[A]]
> Out[42]=Arg[(-I Cos[2 P] - Sin[2 P]) Tan[A]]
> 
> This problem appeared at beginning of the computation. I have no idea to deal
> with it, so the expressions become longer and longer during the computation.
> Can somebody help me?

Hi,

In[]= cc = (-I Cos[2 P] - Sin[2 P]) Tan[A]

In[]= FullSimplify[Abs[cc], Element[{A, P}, Reals]] // InputForm
Out[]= Abs[Tan[A]]

Until you don't know the value of A>Pi/2 or not, no one can calculate
the argument.

Hope that helps
  Jens


  • Prev by Date: Re: working with large strings.
  • Next by Date: Re: number types
  • Previous by thread: Re: a question about complex variable
  • Next by thread: Re: a question about complex variable