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 Sep 30 awarded Curious Jul 5 comment Simple method for detecting grid intersection with circle The algorithm will find it, provided you compute $p_{ij}$ correctly: it the circle's center is in the same grid row or column as the cell in question, the closest point $p_{ij}$ will be on the cell edge, not in the corner (one coordinate will be the same as the center's coordinate). Oct 22 comment Name of a simple recursive smoothing scheme Thanks a lot! For the record, wikipedia has a section on it at en.wikipedia.org/wiki/Moving_average#Exponential_moving_average. Oct 22 accepted Name of a simple recursive smoothing scheme Jul 10 awarded Yearling Jun 6 asked Name of a simple recursive smoothing scheme Oct 15 comment matrix calculus equation - least squares minimization Right, that would be a degenerate case. Oct 15 accepted matrix calculus equation - least squares minimization Oct 15 comment matrix calculus equation - least squares minimization I like this "by inspection" (seriously; though it is "obvious" only if you had done that derivation properly in your life already, I guess). Though the use of pseudo-inverse is not necessary, the system is not over-determined ($A$ is unknown vector, and the zero conditions hold for all derivatives with respect to $A_i$); I should have stressed that perhaps. Oct 14 comment basis/test/Ansatz functions: difference? @joriki: I am sorry, I will read it over and over. Thanks for your effort, appreciated. Oct 14 accepted basis/test/Ansatz functions: difference? Oct 14 comment basis/test/Ansatz functions: difference? I think it is clear now: test functions are subspace's base functions. Thanks! Oct 14 comment basis/test/Ansatz functions: difference? When you say "test function is a linear combination of basis functions", do you then imply that Ansatz=test=trial(=blending?) functions refer to basis of a selected subspace? Oct 14 comment basis/test/Ansatz functions: difference? I actually encoutered most of those terms in literature on Ritz/Galerkin methods. I checked the Ritz's article (referenced from wikipedia), he does not give any name to the function $\psi_i$ he uses in there, though he calls the $a1\psi_1+s2\psi_2+\cdots$ Ansatz (perhaps just in the sense of "formulation" or "expression"). Oct 14 comment basis/test/Ansatz functions: difference? The formulation was not precise, I meant that test function is a function in finite basis, while basis function is function in (possibly infinite) basis. Oct 14 asked basis/test/Ansatz functions: difference? Oct 13 comment matrix calculus equation - least squares minimization $\Phi$ is not invertible, being rectangular. If it were, the solution would get simplified as you say. Oct 13 comment matrix calculus equation - least squares minimization I guess you assumed my problem was over-determined, but in fact it is not: there is as many elements in $A$ as there is conditions on the derivative. Hence pseudo-inversion does not come into play at all, explaining why I god the closed-form solution. Oct 13 revised matrix calculus equation - least squares minimization add link to weighted least-squares Oct 12 revised matrix calculus equation - least squares minimization remove last simplification