198 reputation
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location Washington, DC
age 19
visits member for 3 years, 3 months
seen Jul 18 at 4:02

Feb
27
comment Wolfram Alpha's Mysterious Trig Abilities…
I like this because it's so visual. Accepted!
Feb
27
comment Wolfram Alpha's Mysterious Trig Abilities…
why do this instead of using the sum->product formula?
Feb
27
comment Wolfram Alpha's Mysterious Trig Abilities…
I don't know why this got so many votes... It was just a small error in arithmetic.
Feb
27
comment Wolfram Alpha's Mysterious Trig Abilities…
@Ted forgot to omit that irrelevant part of the question. Fixed
Aug
17
comment Ways to define a curve
@JayeshBadwaik Yes, they are
Aug
17
comment Summation of an Arithmetic, Parametric Sequence
Ok, but that still doesn't answer my first question. How EXACTLY did you get from D(n,r) = D(n−1,r) +(n−r) to the addition of those two summations (i and j)?
Aug
16
comment Summation of an Arithmetic, Parametric Sequence
Also, if I may prick your brain =), how did you so quickly realize that D(n,r) equaled D(n-r,0) + D(r,r) or that D(n,n) equaled n(n+1)/2 or that D(n-1, r) + (n-r) equaled D(n-1,r-1) + r? Are there some generic rules I'm not aware of?
Aug
16
comment Summation of an Arithmetic, Parametric Sequence
Thanks for sharing your insight, but I'm still a bit confused. I thought you'd have to take D(n-1,r) out of the equation in order to perform summation since it merely acts as a symbol for recursive addition of all preceding terms (which is taken care of by the summation). According to your answer, SUM(n-r) is equal to SUM(D(n-1,r-1)) while SUM(r) is equal to SUM(D(n-1,r)). I don't see how D(n-1,r) and D(n-1,r-1) could have any direct value considering they are just indicators that the sequence needs to be summed.
Dec
15
comment Ways to define a curve
Solve the equations, and I use c++
Dec
14
comment Ways to define a curve
That's some useful software, but do you know of any libraries that i can actually incorporate into my physics engine?
Dec
14
comment Calculating Intersection of an Ellipse and a Line
@J.M. Ok good to know. Do you have any info reguarding my other questions?
Dec
14
comment Ways to define a curve
@Emmad That would be great! What software/ math libs do you suggest for finding intersections? I'm pretty sure I can get the movement of all the edges of my bodies down to a single equation that depends on time.
Dec
13
comment Calculating Distance of a Point from an Ellipse Border
Thanks for the helpfulness, let me know if you can think of any other less-precise, faster methods for approximating the distances!
Dec
13
comment Calculating Distance of a Point from an Ellipse Border
Great! that clears a lot up, but I have only a few more questions: The quote says this is the "best approximation;" so how accurate is the equation exactly? Also, do you know of any less expensive (in terms of # of calculations) formulas that would be acceptable for use in a physics engine?
Dec
13
comment Calculating Distance of a Point from an Ellipse Border
A little explanation would be nice.... What's the function PE(u,v) represent, and what's 'u', 'v' and 't' represent?
Sep
24
comment How to calculate the resulting velocitys and rotation speed after two concave polygons collide in 2d
:Can you point me to a more specific explination, or tell me what to search for to get the right results? Also some things don't make much sense... =p (is "perpendicular to the vector to the CM" a typo?) Thanks for replying!
Sep
24
comment 2D elastic collision equation: How does it work?
:Is ''−ysinϕ'' the same as ''+cos(phi+pi()/2)*y'' ? and does this mean collision is totally different with friction =(, or can i apply this equation?
Jul
21
comment Equation to check if a set of vertices form a real polygon?
could you maybe write out the algorithm you think would transfer best to c++ application? Even if i could find a pdf of computational geometry I don't think i would be able to find the equations you speak of...