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location Zurich, Switzerland
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visits member for 2 years, 6 months
seen Mar 19 at 17:54

Jan
11
comment Circle intersection in radial coordinates?
@leo: I specifically need the $\theta$ for the application. But actually you are right - I could solve in rectangular coordinates and then calculate theta after having the two points (x,y) coordinates.
Jan
11
comment Circle intersection in radial coordinates?
@Clayton: Then they would not qualify as their interiors would be disjoint. See second sentence of post.
Jan
11
comment Two circles overlap?
Yes, it seems obvious now. Thank you.
Nov
8
comment Derivative of $x \over x+k$?
For some embarassing reason I can't explain I thought that because the numerator and denominator shares the $a$ term the Quotient Rule didn't apply. Sorry.
Nov
2
comment Combined Partial Derivative?
I know how to apply chain rule with a 1D list, but how does it apply to this diamond shaped graph?
Oct
26
comment How is $dx \over dy$ different from $\partial x \over \partial y$?
math.stackexchange.com/questions/221755/…
Oct
26
comment How is $dx \over dy$ different from $\partial x \over \partial y$?
Now I am really confused. If we plot in 3D a surface $x=z_1z_2$, then at a given point on the surface the tangent in the $z_1$ direction will correspond to the partial derivative $\partial x \over \partial z_1$. Does the total derivative have a similiar geometric interpretation?
Oct
26
comment How is $dx \over dy$ different from $\partial x \over \partial y$?
But for all mechanical purposes all the same rules apply in both cases? We are asking how the "numerator" variable varies with respect to the "denomiator" variable, assuming everything else is held constant.
Oct
26
comment How is $dx \over dy$ different from $\partial x \over \partial y$?
So what does $dx \over dz_1$ mean? Or is it undefined? If it is undefined why not just use the same notation?
Oct
15
comment Generously Feasible?
Can you provide the link? It doesn't show in my search results?
Sep
21
comment Counting Hexagons in Triangle Grid Recurrence?
@BrianM.Scott: What was your technique?
Sep
17
comment Counting Hexagons in Triangle Grid Recurrence?
This is correct, thanks. I was fooled by the N=4 case into thinking that all hexagons that touch all three sides must have one side of n-2, which is true for N=4 but not true for higher values of N. For example for N=5 we can have a hexagon that results from chopping off triangles of side 2 removed from each corner of the grid.
Sep
8
comment N unlabelled balls in M labeled buckets
This proves it incorrect, however I still don't see what went wrong in my reasoning. The number of ways to put N labelled balls in M labelled buckets is $M^N$ correct? So why can't I just divide by the number of permutations of N balls to arrive at the unlabelled ball case?
Sep
8
comment N unlabelled balls in M labeled buckets
Why isn't my expression correct?
Aug
28
comment Closed form for $T(1) = K, T(x) = xT(x-1) + x$?
Yes $x \in \mathbb{Z^+}$
Aug
27
comment Combinations of nonincreasing sequences within bounds?
See my answer for what I was looking for. I guess you were thinking general solution or nothing. I just wanted a way to calculate it.
Aug
26
comment Combinations of nonincreasing sequences within bounds?
@GerryMyerson: I think you may have misread the problem. I have added an example where $a_1 > a_2$.
Aug
26
comment Combinations of nonincreasing sequences within bounds?
@GerryMyerson: What do you mean? $a_i$ can be any integer, as can $b_i$. Obviously if for some $i$, $a_i > b_i$ than the answer to the question is zero. Likewise if for some $i$, $b_i < a_{i+1}$ then the answer is also zero.
Aug
25
comment Elementary power equation: $k_1k_2^x = k_3k_4^x$
Wow, it seems obvious now - exponentiation becomes multiplication in log space - as multiplication becomes addition
Aug
25
comment Elementary power equation: $k_1k_2^x = k_3k_4^x$
I've always found it unintuitive for some reason that $\log_c(a^b) = b\log_c(a)$. I find it hard to visualize a physical model that demonstrates this.