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Studying maths in a higher semester.


17h
revised Why does $(\vec{v}\cdot\vec{u})\vec{u}\neq(\vec{u}\cdot\vec{u})\vec{v}$?
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17h
comment Why does $(\vec{v}\cdot\vec{u})\vec{u}\neq(\vec{u}\cdot\vec{u})\vec{v}$?
@BenjaminLoya Yes, see my answer. If $u\nparallel v$, the inequality holds. This means that $u\ne \lambda v$ for any $\lambda\in\mathbb R$.
17h
answered Why does $(\vec{v}\cdot\vec{u})\vec{u}\neq(\vec{u}\cdot\vec{u})\vec{v}$?
18h
comment calculating the average of updating memory on Interview questions?
Try to compute the expected value for small values of $n$. Do you notice a pattern?
18h
comment calculating the average of updating memory on Interview questions?
Not really. This is the set of indices where $\pi(i)$ is bigger than any $\pi(j)$ before $i$. $\pi(k)$ can basically be seen as the absolute ranking in the sizes of the $k$th entering person.
18h
comment calculating the average of updating memory on Interview questions?
A formalized version: Given a random permutation $\pi\in S_n$, what is the asymptotically expected size of $$\{i | \pi(j) < \pi(i) \forall j < i\}$$
18h
comment Find all solutions for a complex logarithm
@user141183 Because the principle branch choses the angle $\theta\in(-\pi, \pi)$. The angle equivalent to $6 \bmod 2\pi$ and in this interval is $6-2\pi$.
18h
comment Find all solutions for a complex logarithm
@user141183 I don't understand your question. Do you want a closed form representation of $\cos(6)$ and $\sin(6)$?
18h
revised Find all solutions for a complex logarithm
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18h
answered Find all solutions for a complex logarithm
19h
comment What is the $n$th term of this sequence?
@HagenvonEitzen As with all pattern-recognition questions :P
19h
revised What is the $n$th term of this sequence?
edited tags
19h
revised How to compute Dottie number accurately?
Fixed a sign error from C&Ping the \alpha_1 TeX code.
19h
comment How to compute Dottie number accurately?
@Oğuzİsmayiluysal Try wikipedia it also has links to many other languages in the sidebar, so you can probably find the one for your mother tongue from there.
19h
revised If $q\neq 0$ and $e$ are column vectors, when do we have $A$ such that $Aq=e$?
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19h
comment If $\mu$ is a (sub-)probability measure on $\mathbb{R}$, then $\mu(\left\{x\right\})=0$ for all continuity points $x$ of the DF of $\mu$
How about $\mu(A) := \chi_A(0)$? That's a probability measure on $(\mathbb R, \mathcal B(\mathbb R))$ with $\mu(\{0\}) = 1$ (i.e. the only possible outcome is $0$).
19h
comment How to compute Dottie number accurately?
@Oğuzİsmayiluysal It's not the inverse, it's the derivative!
19h
revised If $q\neq 0$ and $e$ are column vectors, when do we have $A$ such that $Aq=e$?
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19h
comment If $q\neq 0$ and $e$ are column vectors, when do we have $A$ such that $Aq=e$?
@yurnero Actually you can only chose a diagonal matrix $A$ if $q_i = 0 \Rightarrow e_i = 0$ holds. You can then define $0\div 0:= 1$ or any other number. If you have $q_i = 0 \wedge e_i \ne 0$, you can't chose a diagonal matrix $A$.
20h
answered If $q\neq 0$ and $e$ are column vectors, when do we have $A$ such that $Aq=e$?