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"Big" Conjugates

Started by Samith Jun 25, 2004 at 7:20 PM 6 replies 1.1k views
Original Post
Samith
Samith
Is it possible to find the conjugate of something like this:

a + b<sup>1/2</sup> + c<sup>1/2</sup>
So far I've come up with multiplying it by
a - b<sup>1/2</sup> - c<sup>1/2</sup>
which leaves you with
a<sup>2</sup> - b - c - 2(b<sup>1/2</sup>c<sup>1/2</sup>)
then you can multiply that by
a<sup>2</sup> - b - c + 2(b<sup>1/2</sup>c<sup>1/2</sup>)
As far as I know, this should get rid of all the square roots, but I don't know if I'm doing all the math right. And there is probably a simpler way to do conjugates like that. This isn't homework. (I'm trying to see if there is anything interesting in complex space)
RenderTarget
RenderTarget
Which parts of the above are imaginary? Or do I not get what you're doing?
[sub]My spoon is too big.[/sub]
Samith
Samith
Ok sorry, when I started writing the post I had a different idea in mind than when I finished :p

Ok, so, to clarify, I'm finding the conjugate of a 3d complex number, i and j both being the square root of -1, but i is on the y axis and j is the z axis. It should be this:
a + bi + cj

So then you'd multiply it by this:
a - bi - cj

and would end up with this:
aa - bibi - cjcj - 2bicj= aa + bb + cc + 2bc

and that was confusing me for a while, I wanted to get rid of the 2bicj, but if i and j are both sqrt(-1) then they would cancel themselves out, so basically that's a solution (I think? Maybe someone can find something wrong with it?)
RenderTarget
RenderTarget
Well, if i == j, then

a + bi + cj == a + (b + c) i

so the conjugate is

a - ( b + c ) i

But, I don't think that's what you're really after.

I think the idea of a 3D complex number is flawed, because there aren't two ways of saying -11/2; so if two of your dimensions are in terms of that, they'll project onto each other. (i == j)

The binary notion of complex numbers is a consequence of things either being imaginary or real. There isn't a true third class of numbers that has a useful analog to real/imaginary, so a 3D complex number doesn't mean much in terms of conjugation--otherwise, it's just a 3-tuple.
[sub]My spoon is too big.[/sub]
Samith
Samith
I know, the concept sucks but maybe it will work with the way I'm doing it :D
szinkopa
szinkopa
This is the area of quaternions.

You have 1,i,j,k

i*i = j*j = k*k = i*j*k = -1

This is the definition for i,j,k

From this you can find that i*j=k, j*k=i, k*i*=j, j*i=-k, k*j=-i, i*k=-j

Nice :)

Multiplication is not commutative, but associative and distributive for addition.

So you get i*j = k
szinkopa
szinkopa
It works only in 3 ways:

1. real numbers, no imaginary units, this is the real number set

2. real part and one imaginary part, this is the complex number set

3. real part and three imaginary parts, this is the quaternion number set

Don't search other combinations, you won't find any without contradictions, this is proven.
Samith
Samith
Wow, thanks szinkopa, good post. I'll read more about these quaternion deals.

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