Aug
28
comment Find the farthest points in d-dimensional space
Why were you interested in a $O(n\cdot 2^d)$ algorithm?
Aug
19
comment Cartesian Product
@DanielFischer: Looks good and easy to understand ; please post as an answer.
Jun
2
comment Integer Linear Programming (ILP): NP-hard vs. NP-complete?
I see. That decision problem is certainly in NP. But is there a polynomial-time algorithm which can use this decision problem to solve the optimization problem? For example, how do you handle unboundedness, and feasibility?
Apr
17
comment Is this a valid way to evaluate a function based on factorials? What would be a better way?
Woah. Where do you usually see such functions?
Apr
9
comment Matrix calculus : Find the gradient/derivative?
$\partial(\operatorname{tr}(Z^T A Z))/\partial X= (A+A^T)X$. Is $A$ symmetric?
Apr
8
comment How do I write it as a sum of a vector and other vector in the orthogonal complement of span?
Welcome to MathSE! I noticed you've asked a few questions but have not accepted any answers. If you found any answers useful, you should start accepting them.
Apr
4
comment Prove that the sequence is bounded.
Thanks for your explanation!
Apr
4
comment Prove that the sequence is bounded.
Can't we find $M$ by taking the limit as $n \to \infty$ (i.e. $M = 2/3$)?
Apr
4
comment Matlab coding help
@DramaFreak: You should start accepting answers. Note that it goes with asking questions.
Mar
28
comment Find the maximum dimensions that will strengthen rod
Or is the strength proportional to $bh^2$ and not $(bh)^2$?
Mar
28
comment Find the maximum dimensions that will strengthen rod
So ... fit the biggest isoceles triangle in a circle of fixed diameter?
Mar
25
comment Definition of sets
You could say $p \in \mathbb{R}^2$ where $p = [x \quad y]^T$. So, $p$ is a point in $\mathbb{R}^2$ space.
Mar
22
comment What does O(n+k) mean verbally
@PooyaM: Don't you mean when $M = f(n)$?
Mar
19
comment Two linearly independent vectors perpendicular to vector $u$
What does the equation $4x + 7y -9z = 0$ mean? It certainly means any point satisfying that equation is perpendicular to your vector. What does it mean graphically?
Mar
18
comment Using the digits $7,7,7,7,1$ and the operators $+,-,*,/$ to make a formula which equals $100$
I'm assuming you can only use the digits once? And you can concatenate the digits to form number?
Mar
7
comment What was the first bit of mathematics that made you realize that math is beautiful? (For children's book)
+1 for $n(n+1)/2$. I "proved" this in the 5th grade using the same method :).
Mar
7
comment Optimizing over norms of set of equations.
Are you looking for a closed-form solution, code ... ?
Feb
27
comment What does the value of a probability density function (PDF) at some x indicate?
A good way of thinking about is $f(x) = \frac{dF}{dx}$ and so it's the rate of change of the cdf at $x$.
Feb
27
comment What does the value of a probability density function (PDF) at some x indicate?
This is a better answer than Alex's but doesn't explain the significance of the number $f(x)$. Does it have a meaning independent of a cdf? Andre's answer of it being approximately $hf(a)$ is great but he doesn't indicate if there's more to $f(x)$ by itself.
Feb
26
comment Minimizing Lagrangian with two functions
+1 => >1000. Congrats :)