2,899 reputation
2827
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location Baltimore, MD
age 29
visits member for 3 years, 11 months
seen Oct 11 at 22:31

I'm a physics graduate student.


Dec
9
comment Solution to $\frac{\partial G}{\partial t}=(1-s)\left(-k_1G+k_2\frac{\partial G}{\partial s}\right)$
Yes, $s\in \mathbb{R}$ and $t \ge 0$. I'll look up the method of characteristics.
Oct
10
comment Why can I exchange the order of integration in a multiple Ito stochastic integral?
In the portion where I set W=s^2, I am not talking about stochastic integrals, but instead just a regular integral, so your criticisms do not make sense.
Oct
10
comment Why can I exchange the order of integration in a multiple Ito stochastic integral?
$(s+ds)^2 - s^2 = 2s ds + ds^2 = 2s ds$
Sep
19
comment Demystify integration of $\int \frac{1}{x} \mathrm dx$
I wrote this blog post about it a while ago. arcsecond.wordpress.com/2011/12/17/… My blog says people followed a link from here to there, but I can't find that link on this page, so here it is. It takes a picture-based approach to the problem.
Jan
31
comment Unusual 5th grade problem, how to solve it
@gmline This wasn't supposed to be a method for enumerating all the answers or anything like that; just a way to approach it visually that might help for some kids.
Nov
29
comment What's the expected value of a lottery ticket?
@cardinal I hadn't thought of it that way, but it's a good point and looks right to me, thanks.
Nov
29
comment What's the expected value of a lottery ticket?
@FlybyNight $n$ is a random variable whose distribution is determined from $p$ and $t$. I believe you do have enough information.
Feb
13
comment Singing Bird Problem
@BrianM.Scott Yes, you're right, thanks. Tried a new answer.
Jan
22
comment Can there be a cubical bubble?
@Rahul Ah, now I see. What I meant is that the performer made a roughly cubical compartment, but it is not perfect. I wanted to know if a perfect cube was mathematically possible, or whether, for example, the corners would always be a little rounded off.
Jan
21
comment Can there be a cubical bubble?
Great answer! Thanks for all the references.
Jan
21
comment Can there be a cubical bubble?
@Rahul Yup, that's what I wanted to know. I just don't really understand how your comment addressed the question. I think there is something about it I'm missing. (I'm not a mathematician.) Will Jagy's answer was pretty much what I wanted.
Jan
21
comment Can there be a cubical bubble?
@Rahul I don't understand, sorry. How does this address whether or not there can be a cubical bubble?
Jan
12
comment How many ways can $b$ balls be distributed in $c$ containers with no more than $n$ balls in any given container?
Thank you. Yes, that was how I got that identity.
Dec
17
comment Fourier transform for dummies
Thanks! I will check it out.
Nov
25
comment Point me the primordial and intuitive concepts about this operations on physics
For an intro to EM, "Electricity and Magnetism" by Purcell is what I used. It was great.
Nov
25
comment Point me the primordial and intuitive concepts about this operations on physics
Well, I'm a physicist and I think I understand electric charge pretty well, but that page still doesn't make sense to me. I suggest finding a better resource.
Nov
25
comment Point me the primordial and intuitive concepts about this operations on physics
what are a, b, and c? It doesn't look like you ever defined them.
Nov
18
comment Fourier-like expansion of a closed curve in 2D
demonstration: youtube.com/watch?v=QVuU2YCwHjw
Nov
18
comment Fourier-like expansion of a closed curve in 2D
We can also think of it as just a usual complex-valued Fourier transform, since complex numbers can represent two dimensions. (I now see that Greg P pointed this out in the comments to the main question.)
Oct
11
comment What is an example of an application of a higher order derivative ($y^{(n)}$, $n\geq 4$)?
I've heard 4th, 5th, and 6th derivatives called "snap", "crackle", and "pop".