2,044 reputation
1230
bio website benalpert.com
location Mountain View, CA
age
visits member for 4 years, 3 months
seen Oct 1 at 21:11

I'm a software developer originally from Boulder, CO, currently working at Khan Academy in Mountain View, CA. In my spare time, I contribute to React, make music, and cook.


Dec
2
comment Kleene Closure and determining whether a string x is in a set
@BrianM.Scott Oops, my bad. I somehow missed the first paragraph and only read the third.
Dec
2
comment Kleene Closure and determining whether a string x is in a set
For the first set, you could also use a parity argument on the length of the string.
Jul
13
comment Can two sets have same AM, GM, HM?
Very nice solution.
Sep
19
comment Mandelbrot-like sets for functions other than $f(z)=z^2+c$?
@Isaac: Many of your pictures seem to be missing now…
Jun
27
comment Choose K items from N in a circle
No problem, hopefully now it's a little easier to understand!
Jun
23
comment Use of “inverse” to mean reciprocal
Yes, I understood that the reciprocal is a type of inverse, but "inverse" seems overly general to specify a reciprocal relationship.
Jun
22
comment Finding $\sin(4a)$ if we know $\cos a$
Please ask your second problem as an entirely new question instead of as an edit to this one.
Jun
21
comment Proving Stewart's theorem without trig
Thanks, your answer is definitely good enough for my purposes. Good night!
Jun
21
comment Proving Stewart's theorem without trig
Very nice, thanks!
May
15
comment Function $F$ that $F(x)+F(-x)=\lim_{y\rightarrow\infty}F(y), \forall x \in \mathbb{R}$
@Tim: Might want to change the title too.
May
10
comment Calculate intersection of 2 points
@J.M. I'm pretty sure Ross Millikan interpreted it right. You have two points and two slopes given as angles from the vertical ($\pi/2$) and want the intersection between the two lines thus determined.
Apr
28
comment Why the name 'FACTORIAL'?
But that's true of other numbers (both smaller and larger) that aren't the factorial.
Apr
26
comment Calculating the highest possible damage achievable using 6 items from a pool of ~25
Probably belongs on SO.
Apr
25
comment Inclusion-exclusion principle: Number of integer solutions to equations
@DAK: Reread Gerry's last paragraph. For the intersection of $A_1$ and $A_2$, it's equivalent to solving $v_1+v_2+y_3+y_4=5$ with $v_1, v_2, y_3, y_4 \ge 0$. Just like the number of solutions to solve $y_1+y_2+y_3+y_4 = 12$ is $C(15,3)$, the number of solutions to that equation (and the size of the $\lvert A_1 \cap A_2 \rvert$ set) is $C(8,3)$.
Apr
25
comment Inclusion-exclusion principle: Number of integer solutions to equations
I agree, I think it's $C(12 + 4 - 1, 3) = C(15,3)$.
Apr
13
comment Can (x'y' + xy) be simplified?
@Brandon: You should probably write that as an answer.
Apr
13
comment Draw customized (calculus) graphs like these?
Not sure whether to flag it, but I have enough rep to retag stuff so I got rid of the graph-theory tag.
Mar
31
comment Interpreting “lying on the parabolas”
Out of curiosity, how do you get Mathematica to make that?
Mar
20
comment Numbers satisfying $\binom{n}{k} = m!$
I just wrote a script and I don't believe there are any others up to 13! (except of course $\binom{n}{0}$ and $\binom{n}{1}$).
Mar
20
comment Is $\nu_1\perp\nu_2$ equivalent to $|\nu_1|\perp|\nu_2|$ for complex measure?
You may want \perp instead of \bot; the spacing is better with \perp.