Drexel dragonThe Math ForumDonate to the Math Forum



Search All of the Math Forum:

Views expressed in these public forums are not endorsed by Drexel University or The Math Forum.


Math Forum » Discussions » sci.math.* » sci.math.independent

Topic: What's the geometry meaning of i^i ?
Replies: 16   Last Post: Jul 29, 2012 2:34 PM

Advanced Search

Back to Topic List Back to Topic List Jump to Tree View Jump to Tree View   Messages: [ Previous | Next ]
Narasimham

Posts: 307
Registered: 9/16/06
Re: What's the geometry meaning of i^i ?
Posted: Jul 27, 2012 1:44 PM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On Thursday, July 26, 2012 1:16:34 PM UTC+5:30, Narasimham wrote:
> On Jul 25, 9:28 am, Hongyi Zhao <hongyi.z...@gmail.com> wrote:
> > Hi all,
> >
> > What's the geometry meaning of i^i ?  Here, i is the imaginary unit.
> >
> > Regards
> > --
> > .: Hongyi Zhao [ hongyi.zhao AT gmail.com ] Free as in Freedom :.
>
> i^i is not an imaginary number or numbers, but a set of equally spaced
> real numbers.
>
> Just as product of two negative numbers returns
> positive,exponentiation of pure imaginary numbers returns as pure real
> number.
>
> From Euler's identity the set (its log actually, missed out before) is seen to be odd multiples of pi/2,
> (4*k + 1)pi/2. Geometrically seen on the Argand diagram they are all

their logarithms are
> on the real axis, say formed by a point of a rolling circle 2 units
> radius rolling on real axis. i.e., (.., -7,-3,1,5,9, ..)* pi/2.
> HTH
> Narasimham


It appears your question in other words is:

What happens to a complex number z when it is raised to 'i'th power, and show geometrically what happens to z, i.e., how it maps.

Actually this is a very good question, not properly addressed in undergraduate books even, at least those that I had chance to read. It is true we cannot visualize it as readily as we can visualize z e^( i theta). It as good special case of z^z. We have

z^i = ( r e^ (i theta) ) ^i = r^i / e^ theta
= ( cos(log(r))+ i sin(log(r)) ) / e^ theta

I could upload 3D plots of real and imaginary parts as functions of modulus and argument of z.

Narasimham



Point your RSS reader here for a feed of the latest messages in this topic.

[Privacy Policy] [Terms of Use]

© Drexel University 1994-2014. All Rights Reserved.
The Math Forum is a research and educational enterprise of the Drexel University School of Education.