Recent content by enricfemi

How about apply physics? It needs both physics and CS.

maybe you should learn it from the model library. start with the model library that contain sound modular.

you can find it in the result modules. before that, make sure you used the frequency solve.

thanks, that's a brilliant construct. i think i have finally understood it.

Thank you, arkajad! So you mean the 1-parameter subgroup generated by vector field can be not exponential map?

I don not know whether I was right or not, please give me a hint. (R3,+) can be considered a Lie group. and its TG in 0 is still R3. suppose X as a infinitesimal generater, it can give a left-invariant vector field and also an one-parameter subgroup. but i think, this one-parameter...

Do you mean this: http://mathworld.wolfram.com/PointLattice.html

Thank you, ystael! I have found Spivak's calculus on manifolds and trying to read it. and so sorry that there maybe a misunderstanding: I know how to prove dy^dx=-dx^dy what i really confusing is why dx^dy=dxdy dy^dx=-dxdy Is it only happened at R3?

I'm reading Marsden's vector calculus. In the chapter of differential forms, it mentions the wedge product satisfies the laws: dy^dx=-dxdy. and for a 0-form f, f^w=fw. Does it have formal derivation? hope someone can give me a hint or even a link.

if a is a constant y=a*f(t) then dy/dt=a*df/dt

Yes, it is ok.

ok,thx

it is only need 2-3 kev for electron to reach 0.1c! is it right?

that is my effort, cherk the nb of mathematica

a electron with speed at 0.1c, what is it energy in the unit of ev. and when should we consider the relativity effects for the electron? thx