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

Topic: -1 x -1 ?
Replies: 29   Last Post: May 13, 2009 9:01 AM

Advanced Search

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

Posts: 5,039
Registered: 12/6/04
Re: -1 x -1 ?
Posted: May 12, 2009 1:30 AM
  Click to see the message monospaced in plain text Plain Text   Click to reply to this topic Reply

On May 11, 11:59?pm, Kayama <yano...@earth.ocn.ne.jp> wrote:
> If we can use the expression -1=e^{i\pi}, we can show
> -1*-1=e^{i\pi}*e^{i\pi}=1 readily:
> if we rotate once 1 (the vector 01) by \pi rad around the origin anticlockwise on the complex plane, we obtain
> -1. Further likewise if we rotate -1 by \pi rad once more, we can obtain -1*-1=1.
> At least I understand -1*-1=1 in this way.
> In that way we can obtain i (imaginary unit), if we rotate 1 by \pi/2 around the origin anticlockwise.
> If we cannnot allow to use the expression -1=e^[i\pi}, I don't understand -1*-1=1 vividly.

If you call North positive and face South (negative
direction) and then take a step backwards (negative
relative displacement) then you've moved North one
step (positive absolute displacemrnt).

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

[Privacy Policy] [Terms of Use]

© The Math Forum 1994-2015. All Rights Reserved.