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13h
comment Decomposition of a nonsquare affine matrix
@acs: I don't see a well-defined question there. If you tell me specifically which equation in the article you're comparing with which equation in my answer, and why you'd expect them to be compatible or not, and what it would mean for them to be compatible, I'll be happy to answer.
13h
comment Decomposition of a nonsquare affine matrix
@acs: There are a whole lot of equations in that article. Which equations are you interested in, and which equations should they be compatible with, in what sense?
21h
comment probability,calculus
This is an almost exact duplicate of math.stackexchange.com/questions/1642329/…. Please don't do that; it wastes everyone's time. If you wanted to add a sentence to the other question, there's an edit button underneath the question for that.
21h
comment Find number of rectangles
No. I doubt much can be said about it in this generality -- the result depends on all the details of $X$.
21h
comment If the $\Pr($hypothesis) is due only to chance, then what is the problem?
@LePressentiment: No, each has probability $1/216$, for a total of $1/36$.
21h
comment Find number of rectangles
You're missing a factor $1/2$ in the count in the last line.
21h
comment If the $\Pr($hypothesis) is due only to chance, then what is the problem?
@LePressentiment: I added an explanation to the answer.
Feb
4
comment Find the number of seating arrangements at a round table of three single men, two single women, and two families
@DreadfulWithMaths: There are $7!/7$ cyclically inequivalent arrangements of the $7$ men, women and family blocks. There are $11$ seats, so each of these cyclically inequivalent arrangements can be placed on the numbered seats in $11$ different ways.
Feb
4
comment Why doesn't Cantor's diagonalization work on integers?
@birna: Yes, it is.
Feb
4
comment Why doesn't Cantor's diagonalization work on integers?
@birna: It doesn't matter how you change the digit, by adding or randomly -- as long as you change each digit, you either have to stop or construct an infinite string of digits. The situation is different for reals because an infinite string of digits defines a real number, but it doesn't define an integer. So you don't have to stop for reals.
Jan
7
comment If the covariance matrix is $\Sigma$, the covariance after projecting in $u$ is $u^T \Sigma u$. Why?
@Shobhit: I'd inferred from the OP's formulation "the covariance after projecting in $u$ is $u^T \Sigma u$" that the term "projection" as used in the question refers to the scalar length of what you're referring to as the "projection" (since otherwise it wouldn't have a scalar covariance). As far as I'm aware, both of these uses of the term "projection" are in common use.
Jan
6
comment Multiple-choice question about the probability of a random answer to itself being correct
@NikosM.: So choosing with a different distribution would not be "choosing at random"?
Jan
3
comment Conditional joint probability, where does the big O come from
It should be $y$ instead of $y'$ in the numerator on the right-hand side?
Dec
30
comment The sign of the complementary minor of a Matrix
It seems that this is already wrong for $2\times2$ matrices, where a minor and its complementary minor are simply elements of the matrix, which can have arbitrary signs.
Dec
30
comment Computing alternating sum using contour integration
There's no double pole at $z=0$. The $\operatorname{sinc}$ function is analytic at $z=0$, so you just have the normal pole from the second factor, the same as at any other integer. About the missing signs, note that $\sin \pi z$ goes like $\pi(z-z_0)$ at $z_0=n$ for even $n$ but like $-\pi(z-z_0)$ for odd $n$.
Dec
25
comment Why is polynomial regression considered a kind of linear regression?
@MichaelHardy: I used to do both at the time, but I've developed more regular sleeping patterns since :-)
Dec
10
comment How many arrangements of banana
@dc3rd: You did, but then you multiplied that by a number of admissible ways of arranging the a's that actually only occurs for one of those $3$ locations of the 'b', whereas it would have to hold for all $3$ positions in order for that product to be the answer.
Nov
21
comment The Light beam Problem.
I think where it says "randomly" you mean "arbitarily"?
Nov
13
comment PMF table probabilities
The question is highly confusing in its present form -- one has to read the comments in order to understand that you answered your own question. Please mark this clearly so that the question makes sense by itself.
Nov
12
comment Sample from distribution taking spherical statespace
That makes no sense. The density function for a two-dimensional manifold must be a function of two variables. It may not depend on one of them, but unless you specify the second variable, you haven't defined a distribution. E.g., a density $\rho(\phi,\theta)\mathrm d\phi\mathrm d\theta=f(\phi)\mathrm d\phi\mathrm d\theta$ would specify a different distribution than a density $\rho(\phi,\sin\theta)\mathrm d\phi\mathrm d\sin\theta=f(\phi)\mathrm d\phi\mathrm d\sin\theta$. Probably you meant the former?