network profile
| bio | website | |
|---|---|---|
| location | Chemnitz, Germany | |
| age | 26 | |
| visits | member for | 2 years |
| seen | May 14 at 15:05 | |
| stats | profile views | 153 |
You can run, but you cannot glide!
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May 15 |
awarded | Yearling |
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Feb 27 |
accepted | Dihedral angles between tetrahedron faces from triangles' angles at the tip |
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Feb 27 |
comment |
Dihedral angles between tetrahedron faces from triangles' angles at the tip Since you were the first one to come up with a solution, it hurts not giving you the credit of acceptance. But I have to make a decision and achille's answer is more elaborate. But +1, of course. |
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Feb 26 |
comment |
Dihedral angles between tetrahedron faces from triangles' angles at the tip +1 Man, of course, the normal vectors with some vector arithmetics, nothing 'bout spherical trigonometry, me stupid! |
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Feb 26 |
comment |
Dihedral angles between tetrahedron faces from triangles' angles at the tip @SSumner Thanks for this link. "But I have no idea how it works" - Well, it has the formulas written on the site (though I'm also not able to directly derive this from spherical trigonometry, but at least I got a formula). Maybe somebody comes up with a nice answer showing the actual derivation of those formulas. |
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Feb 26 |
revised |
Dihedral angles between tetrahedron faces from triangles' angles at the tip added 2 characters in body |
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Feb 26 |
comment |
Dihedral angles between tetrahedron faces from triangles' angles at the tip @SSummer Really? In the end the only thing I'm uncertain of is the bottom plane of the supposed tetrahedron and this plane's location shouldn't change the dihedral angles between the other three faces. The tip's angles should completely define the tip triangles' locations relative to each other, shouldn't it? If I'm wrong on this, you could make the counter-proof an answer. |
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Feb 26 |
asked | Dihedral angles between tetrahedron faces from triangles' angles at the tip |
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Jun 8 |
awarded | Caucus |
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May 15 |
awarded | Yearling |
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Apr 24 |
comment |
What is the formula of the following? I don't currently get what you mean by "the three orthogonal tangent planes". In each point of the ellipsoid you have one unique tangent plane. Or do you mean all triplets of pairwise orthogonal planes that are tangent to the ellipsoid? And of course I second the above three comments. |
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Apr 11 |
comment |
Intersection between 3D closed contour and 3D plane @msotaquira A line-plane intersection is an extremely trivial operation. Come back when your contour has thousands of points to talk about computational expense. |
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Apr 10 |
comment |
Intersection between 3D closed contour and 3D plane @msotaquira Well, then it's not a contour, is it? So you're rather asking for a good way to define a contour using those points, which is entirely dependent on the context and your needs. But using a simple piecewise linear curve, as Mark suggests in his answer (and AakashM assumed in his comment) would be a good start. |
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Mar 13 |
comment |
I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent @t.b. I have never seen it anywhere before, but Ok, according to your link it seems apprpriate. |
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Mar 13 |
revised |
I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent fixed formatting and error in last equation |
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Mar 13 |
suggested | suggested edit on I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent |
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Mar 13 |
revised |
I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent fixed formatting and removed chatter |
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Mar 13 |
suggested | suggested edit on I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent |
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Mar 13 |
suggested | suggested edit on I have to show that the matrix $M^TM$ is SPD if and only if the columns of the matrix M are linearly independent |
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Mar 8 |
comment |
How to define sparseness of a vector? Sorry if my comments are a bit confusing. It isn't the name sparseness that bothers me, it's the hard fact, that your above function (the one with the $\sqrt{k}$) is 1 for a sparse vector and 0 for a dense vector (no matter how you name it). |
