Reputation
5,618
Next privilege 10,000 Rep.
Access moderator tools
Badges
14 31
Newest
 Explainer
Impact
~63k people reached

Jan
25
reviewed Approve Contrapositive - Convergence of a sequence
Jan
21
reviewed Approve Computing the spherical coordinates in n-dimensions
Jan
12
comment Convergence of $\int_0^{\infty}\sin (p(t))dt$
@vnd : Yes, that's my point.
Jan
12
comment Convergence of $\int_0^{\infty}\sin (p(t))dt$
How do you go from a majoration of $e^x f(x)$ to one of $e^x |f(x)|$ (which means you should also have a minoration of $e^x f(x)$) ?
Jan
8
comment Absolute value : Freshman exercise
@ManalBouabdallaoui : I think Ian is suggesting that you examine separate cases depending on the signs of $x$ and $y$.
Jan
5
revised How to find the Haar measure on the group of affine transformations on $\mathbb{R}^n$?
added 35 characters in body
Jan
5
revised How to find the Haar measure on the group of affine transformations on $\mathbb{R}^n$?
Corrected change of variable formula to $d(A'A) = |\det A'|^n \, dA$
Jan
5
comment How to find the Haar measure on the group of affine transformations on $\mathbb{R}^n$?
@Batominovski: Yes, thanks.
Jan
5
answered Why is $\{p \in \mathbb{Q},:p<1\} | \{p \in \mathbb{Q}: p \geq 1\}$ a real number?
Jan
4
answered How to find the Haar measure on the group of affine transformations on $\mathbb{R}^n$?
Dec
24
comment Finding the optimal moves for a puzzle.
If you define a vector $u_i = (u_{i,1}, \ldots u_{i,n})\in G^m$ where the components are $u_{i,j} = 0$ if $j \in S_i$ and $1$ otherwise, then the operator $T_i$ is just $g \mapsto g + u_i$. Essentially you're given vectors $u_1, \ldots u_k \in G^n$, and looking for integers $(N_1, \ldots N_k)$ such that $g + \sum_{i = 1}^k N_i u_i$ is optimal. I don't know if that helps.
Dec
24
comment Calculating $\det(A)$ using permutations.
Have you tried computing this determinant for small values of $n$ (like $2$, $3$, $4$) ?
Dec
20
comment Converting a 1st order non-linear recurrence to a 2nd order
Denote $\otimes$ the inverse operator. It is semi associative meaning there exists another operator $\times$ (which here is the usual multiplication) such that $(a \otimes b) \otimes c = a \otimes (b \times c)$.
Nov
19
comment Determine maximal addend in Newton Binomial Expansion.
I think the expansion should be $$\left(2n+\frac{1}{2n}\right)^{4n+1} = \sum_{k = 0}^{4n+1} \binom{4n+1}{k} (2n)^k \left(\frac{1}{2n}\right)^{4n+1-k} = \sum_{k = 0}^{4n+1} \binom{4n+1}{k} (2n)^{2k-4n-1}$$
Nov
16
comment What is this dynamics question asking me to do?
I think the question is asking you what the limit of this expression is as $u$ goes to infinity.
Nov
16
comment Why is $GL_2(\mathbb C)$ connected?
@learnmore : Well, you don't need to know about Lie groups for this proof (you just need to know about exponential of matrices, which are defined with the usual series $\exp(A) = \sum_{n = 0}^{+\infty} \frac{A^n}{n!}$). I was just mentioning where this idea came from.
Nov
16
answered Why is $GL_2(\mathbb C)$ connected?
Nov
16
revised Finding all group homomorphisms $(\mathbb{Q},+)\to (\mathbb{Q}-\lbrace 0\rbrace,\cdot)$
added 901 characters in body
Nov
15
answered Finding all group homomorphisms $(\mathbb{Q},+)\to (\mathbb{Q}-\lbrace 0\rbrace,\cdot)$
Nov
11
comment How to prove that this ring homomorphism is isomorphic?
Remember the notation $F[x]/(m(x))$ is for the space of polynomials $F[x]$ modulo the ideal $(m(x))$. This not a fraction in the usual sense (which would make no sense here), but a space in which $m(x)$ and all its multiples are zero.