Results 1 to 4 of 4

Math Help - Argument of a complex number

  1. #1
    Super Member craig's Avatar
    Joined
    Apr 2008
    Posts
    748
    Thanks
    1
    Awards
    1

    Argument of a complex number

    Just a quick couple of questions, when working out the argument of a complex number, does the result always have to be between \pi and -\pi?

    Also, if the number was 1 - i for example, is the answer, \tan^{-1}\frac{-1}{1} or \tan^{-1}\frac{1}{1}?

    Thanks for your help, just forgot a couple of things from earlier in the year

    Craig
    Follow Math Help Forum on Facebook and Google+

  2. #2
    MHF Contributor
    Joined
    Sep 2008
    From
    West Malaysia
    Posts
    1,261

    Re :

    Quote Originally Posted by craig View Post
    Just a quick couple of questions, when working out the argument of a complex number, does the result always have to be between \pi and -\pi?

    Also, if the number was 1 - i for example, is the answer, \tan^{-1}\frac{-1}{1} or \tan^{-1}\frac{1}{1}?

    Thanks for your help, just forgot a couple of things from earlier in the year

    Craig

    From what i learnt, the angle \theta has to be expressed in radians with domain -\pi<\theta\leq\pi .

    The argument for z=1-i is tan^{-1}\frac{-1}{1}

    remember , for the argument for a complex number z=x+yi , its argument will be tan^-1\frac{y}{x}
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor

    Joined
    Aug 2006
    Posts
    18,669
    Thanks
    1618
    Awards
    1
    Quote Originally Posted by mathaddict View Post
    remember , for the argument for a complex number z=x+yi , its argument will be \color{red} tan^-1\frac{y}{x}
    That is true only if x>0.
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Flow Master
    mr fantastic's Avatar
    Joined
    Dec 2007
    From
    Zeitgeist
    Posts
    16,948
    Thanks
    5
    Quote Originally Posted by craig View Post
    Just a quick couple of questions, when working out the argument of a complex number, does the result always have to be between \pi and -\pi?

    [snip]
    How you define the principle argument is a matter of convention. eg. 0 \leq \theta < 2 \pi is equally valid.
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. Argument of a complex number
    Posted in the Differential Geometry Forum
    Replies: 2
    Last Post: August 22nd 2009, 01:22 PM
  2. Argument of complex number
    Posted in the Trigonometry Forum
    Replies: 1
    Last Post: April 3rd 2009, 07:06 PM
  3. Argument of a complex number
    Posted in the Calculus Forum
    Replies: 4
    Last Post: January 16th 2009, 08:55 AM
  4. [SOLVED] Argument of complex number
    Posted in the Calculus Forum
    Replies: 8
    Last Post: June 18th 2008, 02:29 PM
  5. argument of a complex number
    Posted in the Calculus Forum
    Replies: 1
    Last Post: April 2nd 2008, 12:08 PM

Search Tags


/mathhelpforum @mathhelpforum