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Sep
13
awarded  Commentator
Sep
13
comment Is there any math operation defined to obtain vector $[4,3,2,1]$ from $[1,2,3,4]$?
It's the called the reverse identity matrix J. J[1 2 3 4]^T = [4 3 2 1]^T.
Sep
10
answered What function is this?
Jul
21
comment Help with a derivative
Just do it the normal way; or take the log of your expression and calculate its derivative.
Jul
20
comment What are the Axiom of Choice and Axiom of Determinacy?
This answer is at the wrong level and self-indulgent. And honestly probably doesn't help the original poster.
Jun
18
comment Good textbooks on combinatorics for self-study
I would not classify this book as introductory at all.
Apr
20
awarded  Editor
Apr
20
revised Transformations of Normal
added 47 characters in body
Apr
20
answered Transformations of Normal
Apr
14
comment Algorithmic Complexity of Iterated Sums
I don't think so. Let f(a,n) := {if (n>1) n*f(a,n-1) else 1} = n!. Then f(a,n) is a polynomial-time algorithm using simple operations but F(n) is not a polynomial-time algorithm.
Mar
16
awarded  Critic
Mar
16
comment Recommend a statistics fundamentals book
If you just want a review, just read Schaum's Outline of Probability and Statistics. It's less than $16 new.
Mar
5
comment Explain $-\int^{a}_{b}\frac{Q}{4 \pi \epsilon \bar{r}^{2}} \cdot d \bar{r}= \left[\frac{Q}{4\pi \epsilon \bar{r}}\right]^{a}_{b}$
In American textbooks, curl is usually written $\nabla \times$.
Mar
5
answered More help with implicit differentiation
Mar
2
comment Line simplification algorithm
Is the shape important or is only the frequency of the teeth important? If only the frequency of the teeth, you can use a color gradient instead. You have 5000 points but only 450 pixels, then split the line into fixed number intervals (each with 30 points for example) and calculate how many teeth there are in each interval. Then color code with red for very few teeth and blue for very many teeth.
Feb
28
comment Mathematical difference between white and black notes in a piano
"harpsichords had to be retuned each time one wanted to play in a different key, right?" No they did not because only some keys would sound disagreable but not all. It is far easier to avoid certain keys than to retune an instrument; a harpsichord can be retuned but not a pipe organ. Sorry, I'm off topic.
Feb
27
awarded  Teacher
Feb
27
answered How exactly do differential equations work?
Feb
27
awarded  Supporter
Feb
27
comment Help calculating a series
I like this more than the choosen answer because it is easily seen to be true.