Date: May 12, 2009 1:30 AM
Author: mensanator
Subject: Re: -1 x -1 ?
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).