7,748 reputation
21032
bio website
location
age
visits member for 2 years
seen 1 hour ago

I'm in the math PhD program at UCLA, focusing on convex optimization.


2d
revised Total Derivative - Application
added 1 character in body; edited title
2d
comment normal cone to sublevel set
Out of curiosity, where did you come across this?
Sep
14
comment Book to self-learn probability
Googling for "probability book math.stackexchange" reveals this thread: math.stackexchange.com/questions/31838/…
Sep
14
comment Differentiating a Quadratic Form
In your first step, the right side changes from a scalar to a matrix, so something is wrong there.
Sep
12
awarded  Yearling
Sep
11
comment Can there be a Finite Field That Does Use Not Modular Arithmetic?
Every finite field is isomorphic to $\mathbb Z_p[x]/\pi(x)$ for some irreducible polynomial $\pi(x) \in \mathbb Z_p[x]$. So we can construct all finite fields in this way, using modular arithmetic (admittedly, modular arithmetic of polynomials).
Sep
11
answered Can there be a Finite Field That Does Use Not Modular Arithmetic?
Sep
10
comment Are there any mathematics “problem websites” similar to Project Euler?
The Alcumus online learning system at artofproblemsolving.com is worth mentioning.
Sep
9
comment How “big” are the mathematical disciplines?
"The sizes of the bubbles reflect the numbers of papers published in the last two decades in each area."
Sep
8
comment Products of Infinitesimals
I'm not sure I'd call this answer "incorrect reasoning". I think this is standard intuition when physicists manipulate $dx$ and $dy$. It might not be rigorous but physicists derive things like this all the time.
Sep
8
comment How to find the derivative of the inverse function $g^{-1}$, when no formula for the function $g$ is given?
@NonymousNT To derive that formula, start with $g(g^{-1}(x)) = x$ and differentiate both sides to obtain $g'(g^{-1}(x))(g^{-1})'(x) = 1$. Now divide both sides by $g'(g^{-1}(x))$.
Sep
8
comment How to find the derivative of the inverse function $g^{-1}$, when no formula for the function $g$ is given?
That formula is definitely useful. So what does that formula tell you $(g^{-1})'(3)$ is equal to?
Sep
8
comment How to find the derivative of the inverse function $g^{-1}$, when no formula for the function $g$ is given?
You'll get a better response if you explain what your thoughts are about the problem, and what you've tried. Are there any techniques you've learned recently that seem like they might help solve this problem?
Sep
7
revised Mean value proof in Evans PDE
added 2 characters in body
Sep
7
answered Mean value proof in Evans PDE
Sep
7
comment I am stuggling with mathematics, and hard to stay focus with it.. Suggestions?
Have you tried Khan Academy?
Sep
7
comment Mean value proof in Evans PDE
Yes, we're using the directional derivative formula. I think the $\frac{r}{n}$ comes from the fact that we are computing averages over balls and surfaces here. Note that $r^n = \frac{r}{n} n r^{n-1}$.
Sep
5
revised Is there a function whose derivative is $|x|$?
added latex
Sep
5
awarded  Nice Answer
Sep
5
comment Reference request: Measure theory and/or manifolds
Manifolds books: math.stackexchange.com/questions/46482/… ; math.stackexchange.com/questions/14475/…