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12h
comment One point following another moving in a straight line?
I'll move this to math.SE, but to help you anyway: what you're interested in is called a pursuit curve.
2d
comment If Q is an orthogonal matrix, does it follow that $QDQ^T = Q^TDQ$?
I really wish people would just try things out sometimes; it's not like failed experiments in mathematics will blow up in your face.
May
24
comment This one weird thing that bugs me about summation and the like
Well, Thiele expansion is the exact analog of Taylor expansion for continued fractions. In this case, instead of evaluating derivatives at your expansion point, you're evaluating reciprocal derivatives.
May
24
comment This one weird thing that bugs me about summation and the like
With respect to the continued fraction: you'll want to look up Thiele expansion and reciprocal detivatives.
May
24
comment Is university math all about proofs?
@John, I'll dispute that; sometimes they just have coffee instead.
May
22
awarded  Popular Question
May
16
revised Why is Cumulative “Density” wrong?
edited tags
May
15
awarded  Nice Answer
May
4
revised Evaluate the limit $\lim\limits_{ x \to 0} \frac {\sin 5 x } {\sin 2 x }$
deleted 12 characters in body; edited title
May
4
revised Why do we still do symbolic math?
added 2 characters in body
May
4
revised Integrating Associated Legendre Polynomials
edited tags
May
4
reviewed Reject mean value theorem sin(b) - sin(a)
May
4
reviewed Close Themes in Mathematics
May
4
reviewed Close Show the $(p-1)! \equiv -1 \mod p/$…
May
4
reviewed Leave Open How to detect different types of curves
May
4
comment How to integrate $\frac{1}{\sqrt{x^2+y^2+z^2}}$
Ah, right; the Jacobian is $r^2 \sin\phi$, so you cancelled everything correctly. The conclusion should now be clear.
May
4
revised What is the reason to use hypergeometric functions?
edited tags
May
4
comment How to integrate $\frac{1}{\sqrt{x^2+y^2+z^2}}$
@rekt, then your integrand times the Jacobian should only be $\sin\phi$, no?
May
4
revised Find the antiderivative for $f(x)=\frac{1}{1+\cos^2x}$
edited tags
May
4
comment How to integrate $\frac{1}{\sqrt{x^2+y^2+z^2}}$
rekt, did you remember to make the coordinate changes in your original integrand?