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Theoretical astrophysics.


1d
comment Finding “Maxima” and “Minima” on a B-Spline
you are right. Would you know how to extract those crossing? (from the graphics rather than using e.g. FindAllCrossings2D).
1d
comment Finding “Maxima” and “Minima” on a B-Spline
Thank you for your interest; it seems it behaves strangely on the edges though; and misses a few extrema as in this example. Still its fast so it might be worth digging.
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comment Finding “Maxima” and “Minima” on a B-Spline
Something like that ought to work? dat = GaussianRandomField[nn = 32] // Chop; dat /= Max[dat]; dat *= nn/2; dat2 = Table[{i, j, dat[[i, j]]}, {i, nn}, {j, nn}]; bs = BSplineFunction[dat2]; dbs = Function[{u, v}, Sqrt[Derivative[1, 0][bs][u, v][[3]]^2 + Derivative[0, 1][bs][u, v][[3]]^2] // Evaluate]; ParametricPlot3D[bs[u, v], {u, 0, 1}, {v, 0, 1}, MeshFunctions -> Function[{x, y, z, u, v}, dbs[u, v]], MeshStyle -> Directive[AbsolutePointSize[Small], Red], Mesh -> {{0}}]
1d
comment Finding “Maxima” and “Minima” on a B-Spline
could it be used to my problem? mathematica.stackexchange.com/q/9928/1089 just a thought?
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comment Finding “Maxima” and “Minima” on a B-Spline
Very nice use of 1D MeshFunction
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revised Finding “Maxima” and “Minima” on a B-Spline
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revised Finding “Maxima” and “Minima” on a B-Spline
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comment Find the values of parameters so that the matrix is symmetric positive definite
Symmetric is easy; definite is also easy via the determinant.
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revised Finding “Maxima” and “Minima” on a B-Spline
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1d
answered Find lengths of contours in a ContourPlot
1d
comment FindRoot in range
You could also use y /. FindRoot[Sin[y] == 0, {y, #}] & /@ Range[7] // Union
1d
answered Finding “Maxima” and “Minima” on a B-Spline
2d
revised Identifying critical points of 2/3D image/cubes
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revised how to differentiate formally?
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comment Identifying critical points of 2/3D image/cubes
@RahulNarain because critical points are at the intersection of such surfaces?
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revised Identifying critical points of 2/3D image/cubes
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awarded  Good Answer
2d
comment Can Mathematica do symbolic linear algebra?
What about this answer? mathematica.stackexchange.com/a/16378/1089
Apr
19
comment Different Poincaré maps for same Equation
Nice plot! Looks like pastel.
Apr
17
revised Identifying critical points of 2/3D image/cubes
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