304 reputation
18
bio website
location Prague, Czech Republic
age 34
visits member for 3 years, 5 months
seen Nov 16 at 18:45

Nov
15
asked Inertia tensor of a triangle in 3d
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