Jens
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 Aug 24 answered Customizing display of partial differential equations Aug 24 comment Customizing display of partial differential equations I can't resist pointing out that suppress is written with two p... Aug 24 answered Table with dynamic iterator Aug 24 reviewed Close ToExpression from commandline Aug 24 comment Under what conditions does Mathematica give a natural antiderivative when integrating? @Anixx I don't think it's a bug in the 1/(x-1) case - it's a situation where the inverse Fourier transform involves a Cauchy principal-value integral (otherwise it's undefined). This seems to be a genuine counterexample to the thesis that all anti-derivatives of Fourier-transformable functions lead to the same unique choice of integration constants for both methods. I.e., the answer to your question is: there are no obvious general necessary and sufficient conditions that I would be able to formulate. But at least it works for many cases, including polynomials. Aug 24 comment Can we teach Mathematica about functional differentiation? @chris Sure, Mathematica probably can't do the limit in that case. But that's still better than getting a wrong result for that case, as you would with the accepted answer. Anyway, if you have an integral, are you sure you don't want the variational derivative instead of the functional derivative? Aug 24 answered How to combine objects from different .obj files? Aug 24 answered Under what conditions does Mathematica give a natural antiderivative when integrating? Aug 22 comment Horizontally compress a picture with varying compression ratio Do you mean that the part of the image from the left to the horizontal fraction x should be compressed, and that this compressed part of the image should replace the original part of the image? Or do you just want to get the left part of the image by itself? And by compression, you do you mean that you just want a quick display of that process or you actually want a new image with the result? The difference is that the display can be done without any image manipulations (image manipulations are quite slow in Mathematica). Aug 22 comment On using DiracDelta[t] in OutputResposne in version 10. Different result from version 9 I see this issue too (version 10 on Mac OS X). The result is correct if I replace the delta function by 1000 HeavisideTheta[1/1000-t]. Seems like this would have to be called a bug... Aug 21 answered Poincaré Section Aug 21 comment ArrayPlot copied to PDF shows blurred mesh I don't understand why you post this as a solution. Have you actually tried it? Then you must be seeing something in the FullForm of the PDF that I am not. Aug 20 comment ArrayPlot copied to PDF shows blurred mesh I tried CopyToClipboard and got a slightly better looking result in a Mac, I do still see very fine lines when magnifying in Preview... so I guess this is worth a bug report. Aug 20 comment ArrayPlot copied to PDF shows blurred mesh I also see this issue. Perhaps you can use one of the answers to this question instead: Plotting large datasets. A simple way to display the array is Image[1. - IdentityMatrix[4], ImageSize -> 360]. Aug 20 comment How to combine one or more rotated graphics objects? Perhaps you can also make use of this: How to create custom Graphics primitive? Aug 20 reviewed Leave Open How to combine one or more rotated graphics objects? Aug 20 comment Avoid writing explicit form of operator Your edit looks much more complicated since it starts with the fourth functional derivative, and also the component notation seems to indicate that $J$ is a four-vector. I assumed that the main question was how to write a generic differential operator, but I think you're looking for a coordinate-independent way of working with a specific operator in variational calculus. Maybe you'll find what you need in this answer. Regarding my answer, I guess I could have simply set g==1 to make it simpler, but anyway it's not going to help much... Aug 19 comment Coordinate extraction and manipulating graphs as graphics objects There is one fundamental problem with this approach based on GraphData: the VertexCoordinates are only given as approximate real numbers, so that the coordinates that you can extract from the Graphics are not the exact geometric values. Basically, I think the information in GraphData is limited to the number of digits that can be visually discerned in a graph display, so you shouldn't use them for high-precision calculations. Not sure why they didn't implement exact values here... Aug 19 comment Hyperlinks not preserved when saving in PDF format in MMA V10 I think you should file a bug report at wolfram support. I do see the same issue here on OS X. On a Mac, you can use the built-in TextEdit to add hyperlinks using Apple-K. That's perhaps a workaround: copy the Mathematica document as plain text and add the links in TextEdit. Aug 19 revised How can I prevent ColorFunction from disabling antialiasing in graphics? version 10 update