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Jan
22
comment Why does Mathematica add Hold to the result of my user defined symbol?
Just a small comment, you don't need to Unprotect Times or Plus. It is better if you do: mat /: Times[c_, mat[0]] := mat[0].
Jan
9
comment Computing a sequence by recurrence
Is k1 an arbitrary function? If yes, then FoldList which seemed to be the way to do it no longer works.
Dec
18
comment coordinate system problem
Yes, I think ImageData is the best function if you need to access directly the pixel values. Check the documentation, maybe some of its options are useful for your case of use.
Dec
18
comment coordinate system problem
I see, that's a Graphics tool, and those are "plot" coordinates, so they start bottom left. That means that you have to do height - coordY to get the row number.
Dec
18
comment coordinate system problem
How do you access the pixels of the image? Remember that you can see an image as a matrix, where the first row is the top row of pixels. This is why ImageData[image][[1]] represents the top row.
Dec
18
comment Difference between Association and Dispatch
Association keys cannot be patterns (they behave like they had Verbatim), that's the main difference with common rules. Try _Integer /. Association@{_Integer -> Null}, you will get the Null value.
Dec
18
comment Why is C-compiled (but not WVM-compiled) code so slow in Manipulate?
I don't have anymore M8, so cannot test there, but tested it in 9 and 10 and worked fine.
Dec
17
answered Why is C-compiled (but not WVM-compiled) code so slow in Manipulate?
Dec
17
awarded  Custodian
Dec
17
reviewed Reject Manipulate plot
Dec
17
comment Animate skips frames and hard to control speed.
Also check ArrayPlot, I think it is faster than MatrixPlot, and you might try to precompute stuff, like the Prime[Range[400]], not big overhead, but you can keep the list in a variable. Also writing it all as an expression is slightly faster than with pure functions just applied once.
Dec
13
awarded  Citizen Patrol
Dec
1
comment How should I correct in the sintaxis of URLExecute
Second parameter of URLExecute are GET/POST parameters. Your "Method" and "Headers" should be options of URLExecute, not the second parameter.
Dec
1
comment ImportString JSON possible bug
Are you using Windows? I've seen that before in a Windows computer. He got rid of the problem after updating the operative system, but not sure if it was just coincidence.
Dec
1
comment Using SendMail with new Google Security Rules
SendMail uses SMTP, and as far as I see, that protocol is under the "less secure apps" yet.
Nov
27
comment Compact Map of USA with Alaska and Hawaii shown under California
Unfortunate, Inset is the best answer to your question yet. Maybe an improvement could be placing it automatically using GeoDestination + GeoDisplacement instead of writing yourself the coordinates for the Inset.
Nov
27
answered Combine Stereographic “Entity” Plot of Arctic Sea with Contour Plot
Nov
4
awarded  Popular Question
Oct
30
awarded  Good Answer
May
4
awarded  Enlightened