new to quaternions

lol... so I have to understand quaternions if I ever want to understand graphics technology that's older than 1995...

I know why quaternions are used in rotation (because of some problem with rotation locking under certain circumstances with traditional matrices -- it's happened to me and apparently is unavoidable unless using quaternions)

and quaternions are based upon some fundamental associations with the imaginary number 'i' (square root of -1), right?

So how come when quaternions are actually used, this imaginary number 'i' is nowhere to be seen?  I'm totally lost on examples as well as when reading peoples' source code where quaternions are used in calculations.

Even experienced graphics programmers tell me they don't "completely" understand quaternions themselves, they "just use them".  But I'm relatively retarded and I have to understand something down to the very core before I feel confident using it... so... what's up with quaternions?  Linear algebra is one of the few mathematical subjects I had the least trouble with when I was in college but we never touched upon these things :/

All that I know about them are that they are represented in a form not dissimilar from this: Q = a+b*i+c*j+d*k.

You've peaked my interest to read more up on them, so I'll get back to you when I know more.

Isn't quaternions the crazy vector math that uses different square roots of -1 as its base vectors?  Off to Wikipedia!

i^2 = j^2 = k^2 = ijk = -1

zoomj!

>>3
"It is as unfair to call a vector a quarternion as to call a man a quadruped"
--Oliver Heaviside

>>5
What if he spent his life on his hands and feet? Or a vector is modelled as a moving object which merely doesn't travel 1 spacial dimension?

>>6

What if he spent his life on his hands and feet? He'd have a fucked up back.

You need atleast 1 spatial demension to move, unless I didn't quite get what you ment

Okay... so, quaternions have the same similar purpose as vectors (direction, or change in location), but they're ... matrices with imaginary numbers?

I still cannot "get" why imaginary numbers are relevant in rotation, how and why they were introduced by whoever came up with quaternions, and how they suddenly don't exist in calculations in source code when quaternions are actually used in software.

but they're ... matrices with imaginary numbers?
No, they're just simple numbers, which happen to 'contain' four reals.

This might be useful: http://en.wikipedia.org/wiki/Quaternions_and_spatial_rotation#Quaternion_rotation

I doubt you really need to understand all the math just to use software based on it though...