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 Sep 23 comment How to find a suitable contour to integrate round? You're on the right track, compare my answer with your last expression; then use Mariano's hint. Sep 23 comment What concepts were most difficult for you to understand in Calculus? Community wiki I suppose. Sep 23 answered How to find a suitable contour to integrate round? Sep 23 comment Formula(/How) to find 2 numbers that add together to give one number and times to give another "So this Vieta must have been a really smart guy, but you've rediscovered his trick." -LOL, thanks for making my day, Agusti! +1. Sep 23 comment How do I divide a function into even and odd sections? Personally, I wonder who first thought of decomposing $\exp(x)$ as $\sinh(x)+\cosh(x)$ Sep 23 comment How to find where $3$ lines intersect. Agreed, the "Unix philosophy" works well in this case: keep the concurrency test and the routine for taking three lines at a time separate. Sep 23 comment How to find where $3$ lines intersect. I was talking about equation 9 in that link, but the three parallel lines "intersecting at infinity" works too. :) Sep 22 comment Formula(/How) to find 2 numbers that add together to give one number and times to give another Short version: it's the Vieta formulae for the quadratic case. Sep 22 answered How to find where $3$ lines intersect. Sep 22 comment Formula(/How) to find 2 numbers that add together to give one number and times to give another You will end up with a quadratic equation when you replace either of c or d in the first equation with something derived from the second equation. Sep 22 comment How to formulate such problem mathematicaly? (line continuation search) The "angle" procedure in the SO answer you linked to finds the arctangent of the line segment's slope; the "nearly parallel" routine relies on the fact that the angle between two parallel/collinear segments is an integer multiple of $\pi$. Sep 22 comment How can I remove rotations from points defining a plane? @George: To make muad's comment explicit: Euler angles is what you need here. The actual rotation matrix is decomposable as a product of three orthogonals; inverting is as easy as transposing all three and multiplying in the reverse order. Sep 22 comment How to formulate such problem mathematicaly? (line continuation search) In short: could you give an example of your algorithm in action? Sep 22 comment How do I prove this sum is not an integer Note that your sum is merely $H_{k+n}-H_k$; a proof similar to the one in the linked question might work here as well. Sep 22 comment How to formulate such problem mathematicaly? (line continuation search) Rather unclear to me; you want to find the unbroken line that is the nearest approximation to those two green lines in your second diagram? Sep 22 answered Looking for closed-form least squares solution of a simplified inverse kinematics problem Sep 22 comment Finding a simple expression - Binomial Theorem @Mike: You've gotten it. :) Sep 22 answered algorithm to calculate the control points of a cubic Bezier curve Sep 22 revised algorithm to calculate the control points of a cubic Bezier curve edited tags Sep 22 comment Find the range of $x$, given $y_{min} \leq y(x) \leq y_{max}$, where $y(x)$ can be any function ( Updated) Dear Ngu, I think people would really love it if we didn't have to wring and squeeze you for details every time you ask a question. As I said in one of your previous questions, explicitly mention any reasonable (to you) constraints your problem has, since attacking a structured problem is much easier than playing blind man's bluff.