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1d
comment Solving the Frenet Serret equations for non-constant curvature and torsion, obtaining parametric equations
So that's what you call a short answer... (+1)
2d
comment ParametricPlot3D for only part of a sphere
@thedude Indeed, I think you're right. I'll change it.
Feb
10
comment How to make a flowchart?
I know you've already thought about this before - see Controlling TreePlot (and GraphPlot) layout issue; but in all its generality this question seems a bit too much work to fit into a single answer... Just another idea without graphs: perhaps one could adapt Circuit drawing in Mathematica to your purposes. Someone has to put in the effort, though...
Feb
9
comment Schrödinger equation for Hydrogen atom
Your solution approach seems overly complicated because it still requires matching the derivatives at $RM$ after already having introduced the (not strictly valid) condition of vanishing amplitude at $10RM$. You may as well do just a single ParametricNDSolveValue up to $10RM$ and solve for the Ei that makes the amplitude vanish at the end point. Then the continuity of the function and its derivative is automatically insured. Also, SCHR2 didn't solve anything when I tried it.
Feb
8
comment Suddenly all outputs begins with a newline… What to do?
It could also have to do with the style sheet. Impossible to tell without additional info. Maybe send the whole notebook to Wolfram support.
Feb
8
comment Double arguments and place of the underscore
Don't use C - it's a reserved symbol.
Feb
8
comment How to numerically solve a 1-d time-independent Schrodinger equation?
@Peltio I know, it's really funny... who said that reading scientific articles can't be amusing? And it shows why sites like this are needed.
Feb
8
comment Restrict Locator to a certain graphic inside Manipulate
@shrx The locator is restricted to the right plot region. I just tried it. It does move to the edge of the region if you click as you describe, but it never leaves that region.
Feb
7
comment How to numerically solve a 1-d time-independent Schrodinger equation?
I think it's easiest to do that kind of normalization with an $r$ integral directly, then you won't need any Jacobian factors. But of course you'll get problems when the high-lying states aren't spatially resolved, as I already said. If you want such states to be represented more accurately, you'll have to modify either MaxCellMeasure or the transformation of variables. Maybe I'll write some more tomorrow.
Feb
6
comment MatrixForm in Mathematica
See in particular point 8 in this post
Feb
6
comment how to generate a 3d graph of HCP crystal structure
added bug tag because of the previous post that's now linked in the question. It's probably OK to have this question for reference.
Feb
6
comment how to generate a 3d graph of HCP crystal structure
This could be made into a valid question by adding the code to reproduce it. I'll just do that because I already did it before...
Feb
6
comment NDeigensystem returns complex non-hermitian error for the calculation of vibrations of a cantilever
Looks like you made exactly the same error as in the link I posted above.
Feb
6
comment NDeigensystem returns complex non-hermitian error for the calculation of vibrations of a cantilever
Closely related: NDEigensystem producing imaginary eigenfrequencies for the vibrations of a cantilever.
Feb
6
comment Fourier-style solutions to differential equations, not piecewise polynomials
@Nasser is right, and I think the question is not specific enough. E.g., what are the boundary/initial conditions? We would need a minimal example to work with. Maybe one can rewrite the whole equation in Fourier space, but that depends on the details. If the spectrum is continuous, you won't gain anything in terms of simplicity of the output, I think.
Feb
6
comment How to numerically solve a 1-d time-independent Schrodinger equation?
If you don't have analytic comparison functions, then there is nothing to compare to, right? So there's nothing to do, since the eigenfunctions in NDEigensystem are already normalized by default. If you're asking about something else, it's better to start a new question.
Feb
5
comment Generation of Space Representation of non-crystallographic Point Groups
I could do it for 2D (since we know where the polygon vertices are), but I think you're asking more generally about 3D... and I don't have a good general answer for that.
Feb
5
comment How to numerically solve a 1-d time-independent Schrodinger equation?
I just used the $r\to 0$ limit because at random other points you could accidentally get a divide-by-zero error when doing the normalization the way I did. Integrating to normalize seems way too costly for simple comparisons, but it's certainly an option. The eigenfunctions near zero energy do become very oscillatory in the transformed variable, so both NDEigensystem and NIntegrate will need a lot of points to get things right.
Feb
5
comment General function for the expansion of a polynomial of operators
You probably meant this as a comment to my answer, but accidentally posted it in a new answer box. Thanks for the suggestion, anyway...
Feb
5
comment Generation of Space Representation of non-crystallographic Point Groups
Not an answer, but there is a way to get non-crystallographic point groups with the command DihedralGroup... e.g., DihedralGroup[7]//GroupElements gives you the permutation representation which can be then converted to real space. For other points groups, I guess one would first have to figure out if they're isomorphic to some DihedralGroup[n]. I guess that's a partial answer, but maybe not what you're looking for.