Yiyuan Lee

@Maltysen I suppose you can checkout Facebook's oAuth and what length they use

@Maltysen CSPRNG generated? Or does it contain something like token = AES(user id)?

@Maltysen What's this session token for?

AWS has a year of free usage for some services which IIRC should suffice

I think it would be good to host it on AWS or elsewhere so people can live test it easily

ytho

Hi there

There was a typo in your question - The second root should be $3-2i$

Glad I could help!

You might want to try expanding it out again. Hold on, I'll improve my answer to show you a shortcut.

I believe the answer sheet is incorrect. WolframAlpha verifies : wolframalpha.com/input/?i=x%5E2+-+5x+%2B+7+%2B+i

If you took $(x+a)(x+b) = 0$, then the roots would be $x=-a$ and $x=-b$ instead. This is because if you substitute (either of ) these two values in, you will observe that the LHS really resolves into $0$.

Then that will be the quadratic equation you were looking for. :)

Substitute in $a$ into LHS. Then it becomes $(a-a)(a-b) = 0\cdot(a-b) = 0$.

vectors are fun! I've recently completed a high school project whereby we have to write an interactive 3D sphere. You really learn a lot from it. Thanks and see you too!

that is, if you ever need it^^

in* 3d*

inn 3d*

but the link in my answer in the man thread has some goodies on rotation transforms in 3ds

for describing 3d orientation, yes

the other 3 (euler angles) for orientation. its in the link i gave.

1 for 3d cartesian coordinates (the position)

basically, you need 4 parameters instead of just 3

see this

the flaw of your positioning system is that it does not have enough parameters

i think i understand

hmm.. alright

whats the position, direction and angle for?

to only compute the rotation angle from the initial and final vector, or to rotate a vector about some axis by some angle?

so what's the aim of your program?

wait

feel free to use programming jargon, i'm a programmer as well

sorry, the final vector should be (1/sqrt(2), 1/sqrt(2), 0)

thats awesome

sqrt(2) = cos(t)

since |A| = |B| = 1, this simplifies to

A dot B = |A||B|cos(t)

but what we know is that the dot product of the initial vector, A, and the final vector, B, gives

we assume that we dont know that t is 45 degrees

let the rotation angle (45 degrees in this case) be, say, t

the result will be (sqrt(2), sqrt(2), 0)

we consider rotating the (1, 0, 0) about (0, 0, 1) by 45 degrees

lets take a simpler case

yes, it will!

if you rotate (1, 0, 0) about Z-axis by 40 degrees

the final vector has to be different from the initial vector, or else one can say that nothing has changed

as long as you are rotating a vector about ANOTHER vector, you will be able to compute the angle

because the vector wont have rotated t all

unfortunately it's impossible if you are rotating an axis by itself

yep