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13m
comment Operator and VariationalMethods
Also, I think there's probably a mistake in the functional (the laplacian isn't what you want, I bet). I voted to close because the main issue is the simple syntax problem pointed out above.
2h
comment Operator and VariationalMethods
To amplify what @swish already said: g is a symbol that does not represent the expression you want to insert into VariationalD. You want VariationalD[g[x,y,z],f[x,y,z],{x,y,z}], and then the result will be $2 \left| f(x,y,z)\right| \text{Abs}'(f(x,y,z)) \left(g \left| f(x,y,z)\right| ^2+U(x,y,z)\right)$
6h
comment Export MatrixPlot graphics to PDF
I just remembered that I had asked a closely related question myself in 2012, and that this answer also applies there: Color ramp banding in PDFKit when exporting Raster image Inset to PDF.
6h
revised Color ramp banding in PDFKit when exporting Raster image Inset to PDF
added rasterTrick method
6h
comment Export MatrixPlot graphics to PDF
@Lou New dictionary item - "jens-sastic (adj.): awkward and painful solution to a problem that shouldn't exist in the first place"
10h
awarded  Nice Answer
18h
answered Export MatrixPlot graphics to PDF
22h
reviewed Close Dual core CPU — Mathematica uses only 29% of one core
22h
reviewed Close Power::infy: error using FindFit
22h
reviewed Close What is the meaning of a result of {{}}?
1d
comment Transformation of Derivatives under change of coordinates
Closely related: How to change coordinates of a differential operator? The main thing is to apply the chain rule. This question is simpler than the linked one because the transformation is linear.
1d
reviewed Close if f(x) is O(g(n)), then does it follows that h(f(x)) is in O(h(g(x))?
2d
comment Selectively updating individual graphics in a dynamic, multiple-plot Show
@RonaldMonson In your updated post, the statement that Show expects Graphics is not correct. Besides Graphics3D, it also accepts Legended@Graphics and Legended@Graphics3D. My point is the Plot can produce the Legended output, too, and I automatically account for that.
2d
reviewed Leave Closed Plotting an function defined by an integral
2d
reviewed Leave Closed Visualizing The Crack of The RSA Cryptosystem
2d
comment Selectively updating individual graphics in a dynamic, multiple-plot Show
My advice is that if you can get by without taking apart the output of built-in functions such as Plot, then that's less likely to break in future versions. The introduction of PlotLegends illustrates this. It creates Plot output with Head Legended instead of Graphics. In earlier versions, that didn't happen, so that code relying on the internal structure of Plot output from the old version will not work. My solution doesn't rely on any undocumented internal structures.
2d
comment Customizing display of partial differential equations
@Mr.Wizard Are you saying that there is anything wrong with Format in the context of this question? Note that the question is only about formatting for TraditionalForm.
2d
reviewed Close Counting the zeros in a factorial expansion
2d
comment Counting the zeros in a factorial expansion
You only need to apply DigitCount to the factorial.
2d
reviewed Close Citation of the algorithms used in FindGraphCommunities