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Jan
14
comment An example of a problem which is difficult but is made easier when a diagram is drawn
Unless I'm missing something, the "only if" direction is quite nonobvious.
Jan
14
comment What is the characterstic function?
I'm just a Wikipedia-bot these days. en.wikipedia.org/wiki/…
Jan
14
revised Given change in proportions and assuming minimum movement and a direction, calculate minimum proportion moving in that direction
edited tags
Jan
14
comment Reverse spline interpolation
I find your question hard to understand. How are $(x,y)$ a number of sets? Do you mean you have a set of points $(x,y)$? And how does a smaller number of points "reproduce" a set?
Jan
14
comment How to calculate the square root of matrix $A+B$ perturbatively?
Please don't post the same question to more than one StackExchange site at a time.
Jan
14
answered Given change in proportions and assuming minimum movement and a direction, calculate minimum proportion moving in that direction
Jan
14
comment Given change in proportions and assuming minimum movement and a direction, calculate minimum proportion moving in that direction
That can't be right, because it gives zero for $d=(-0.1,0.2,-0.1,0)$.
Jan
14
comment Connections between the solution of simple ordinary equation, normal distribution and heat equation
If that's all you want to show, then sure (for a particular notion of "simplest"). But that's not the same as showing how it's connected to the central limit theorem and the heat equation, which is what your original question is about.
Jan
14
comment Connections between the solution of simple ordinary equation, normal distribution and heat equation
Sorry, I don't think it makes much sense. You could apply the same argument to any other symmetrical, unimodal distribution and conclude that it should also satisfy $y' = -xy$.
Jan
14
comment How to estimate the value of $e$.
possible duplicate of List of representations of e
Jan
14
comment How to find an ellipse , given 2 passing points and the tangents at them?
@Valentas: And in the formula for Case 2 too! Thanks, fixed.
Jan
14
revised How to find an ellipse , given 2 passing points and the tangents at them?
edited body
Jan
13
comment How do you represent a random choice of random variables mathematically? What is its mean, variance, etc.?
Mixture distribution
Jan
13
revised Why is the left inverse of a matrix equal to the right inverse?
edited title
Jan
13
comment Why is the left inverse of a matrix equal to the right inverse?
Previously: Looking for insightful explanation as to why right inverse equals left inverse for square invertible matrices and If $AB=I$ then $BA=I$.
Jan
13
comment Get the area of a “circle section”
There is a method using calculus, but it is neither better nor easier. Use the geometrical method.
Jan
13
asked If there are $n$ $Y$'s for every $X$, but $m$ $X$'s for every $Y$, then the total number of $Y$'s is $n/m$ times the number of $X$'s?
Jan
13
answered Connections between the solution of simple ordinary equation, normal distribution and heat equation
Jan
11
comment Geometry and natural numbers
Here's another solution for $n=3$: The first two Pythagorean triples are $(3,4,5)$ and $(5,12,13)$. Put $A$ at the origin, $D$ on the $y$-axis at $y=3\times5$, and $B$ and $C$ on the $x$-axis with $x=4\times\frac{3\times5}3$ and $x=12\times\frac{3\times5}5$ respectively. Generalize this method.
Jan
11
comment Is the integral of $\frac{1}{x}$ equal to $\ln(x)$ or $\ln(|x|)$?
Also, if someone can explain what DonAntonio was trying to tell me in the comments on the question, I'd much appreciate it... It's hard to communicate on the internet.