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Mar
18
comment Point closest to a set four of lines in 3D
Ah, you are right.
Mar
13
comment Point closest to a set four of lines in 3D
Shouldn't it be $Ax=2b$ ?
Nov
5
comment Distributions of point charges
Thanks. I updated the link. Great webpage!
Nov
5
revised Distributions of point charges
URL change
Aug
19
awarded  Popular Question
Aug
4
awarded  Yearling
Jul
30
comment What is the name of this shape? (spacetime)
Missing image of the shape. Not easy to answer then.
Jul
3
asked Find the Lipschitz constant of a multi-variate Gaussian density function
Apr
22
awarded  Good Answer
Apr
4
awarded  Curious
Sep
30
awarded  Explainer
Sep
24
awarded  Autobiographer
Sep
4
comment Closed form for the sequence defined by $a_0=1$ and $a_{n+1} = a_n + a_n^{-1}$
I guess positivity of $\varphi$ is one sufficient condition to get the correct behavior. Only a guess though.
Aug
4
awarded  Yearling
Mar
12
comment Is $0$ a natural number?
This question is not related to math, it is the consequence of an ambiguous notation which was used by Dedekind in 1888. To avoid ambiguity, ℕ* is used to exclude 0. I cannot manage to understand how this question is still not closed.
Mar
12
comment Simple combinatorics question - caught off guard!
I see your point, yet I believe it is a shame to have ambiguous statements in math.
Mar
12
comment Simple combinatorics question - caught off guard!
With Wiki, "there is no universal agreement about whether to include zero in the set of natural numbers: some define the natural numbers to be the positive integers {1, 2, 3, ...}, while for others the term designates the non-negative integers {0, 1, 2, 3, ...}. The former definition is the traditional one, with the latter definition having first appeared in the 19th century." In the context, this is ambiguous since "For natural numbers (taken to include 0) n and k", the binomial coef is defined
Mar
12
comment Simple combinatorics question - caught off guard!
Not in my country. In France, we call ℕ* the set excluding 0.
Mar
12
comment Simple combinatorics question - caught off guard!
This is wrong for n=0.
Mar
12
comment Simple combinatorics question - caught off guard!
This is clear and intuitive. However, one would have to take care of the case for which a pair contains twice the same "menu" (n=0), and for which the statement is wrong.