146 reputation
4
bio website silvia-hi.me
location China
age
visits member for 3 years, 1 month
seen Aug 28 at 18:24

I'm interested in data visualization, image processing, ODE/PDE, natural language processing, etc.

I'm currently a freelancer of Mathematica programming / Mandarin teaching / logo design.

Email addr: aquilaabz AT gmail.com; or:

1:eJztk8ENwzAIRUkHyA5ZqdfeMkC6/605Vl8Gg8EykUD6imMb8/hxjvP7vl5EtN/63NpKpVIpqSgBg4XzKbwzvP6PJ/Baa2BvxMxzea1caV2al3zQnId7pHqS1yPsEkPPa8/Yk4c8MzmwjuSNtydp3DsHg/PMwov7o74/ntni4f6nSAbuXcPK8YzyYqy+16u8tnrmYYnq07LOee3pKcJrzX3XrHPnjdaz/if47NVqsWl4tBrJmalsPJF9ZegNYzVPKZ9+c/YGIg==


Aug
23
comment Simplify $\tan^{-1}[(\cos x - \sin x)/(\cos x + \sin x)]$
define simplest please.
Jul
23
awarded  Supporter
Jul
3
awarded  Teacher
Jun
13
revised Compound Poisson process with exponential distribution
added 12 characters in body
Jun
13
awarded  Editor
Jun
13
revised Compound Poisson process with exponential distribution
added 10 characters in body
Jun
13
answered Compound Poisson process with exponential distribution
Jul
21
revised Method for variable substitution in multiple summation
added a tag
Jul
21
comment Method for variable substitution in multiple summation
Yes they are:( I used one of the explicit sum formulas of Chebyshev polynomial (mathworld.wolfram.com/ChebyshevPolynomialoftheFirstKind.html eq.15), which introduces those floor functions.
Jul
21
comment Method for variable substitution in multiple summation
@ Christian Blatter: Thanks very much for your answer. I understand the difficulties of counting lattice points in disk, but if considering the summation region bounded only by integer coefficients planes (like $\sum_k A_k x_k=B$ where $A_k, B\in \mathbb{Z}$), the problem might be much simpler and there might even exist a systematical technique for it. Besides, I'm thinking of using Iverson's bracket to avoid dealing with those tricky boundary conditions.
Jul
21
comment Method for variable substitution in multiple summation
@Patrick Da Silva: Yes I draw 2-dim or 3-dim axes too when I do the transformation by hand :D But if I have many levels of sum, this will be inefficient cause it's hard to draw high dimension, and those floor and ceiling functions and steps$\neq 1$ are bothering. I think I need to treat the whole summation region as a high dimension polyhedron and find a systematical routine to deal with it.
Jul
21
awarded  Student
Jul
21
asked Method for variable substitution in multiple summation