Wolfram Mathematica

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P. Fonseca

12:55 AM

Happy new year! (@Portugal)

C. E.

1:06 AM

@P.Fonseca Happy new year!

4 hours later…

Michael E2

4:39 AM

@halirutan Happy New Year! Nice blog post. Note you don't need to define f::optx because the message system will use General::optx if f::optx is undefined, unless you want to customize the message for f.

halirutan

5:16 AM

@MichaelE2Thank you for pointing that out. I'm going to review the post. It was written kind of in a hurry.

Happy new year to you and all the people here as well.

@MichaelE2 It is indeed very nice that you pointed this out. I remembered something like that but what I wasn't aware of is that the symbol in the message will still be f and not General even if it is not defined.

Do you know that the Message system will not only use the optx message but attach it to f along the way?

Michael E2

5:49 AM

@halirutan Yes, I knew that. And, to quote the Messages tutorial, "You can use Off[F::argx] to switch off the argument count message specifically for the function F. You can also use Off[General::argx] to switch off all messages that use the text of the general message."

2 hours later…

Alucard

7:39 AM

happy new year guys

2 hours later…

halirutan

9:16 AM

@MichaelE2 I fixed it in the blog post.

2 hours later…

Artificial Stupidity

11:28 AM

Can anybody here know the following Fractal-like figure? What is it?

The filename is sin(x^2+y^2)=t, do you have any idea?

1 hour later…

halirutan

12:52 PM

@ArtificialStupidity It doesn't look like this is the used equation.

Artificial Stupidity

1:12 PM

@halirutan probably t is a function of something.

halirutan

1:31 PM

@ArtificialStupidity Let me think. It might be possible that the additional rings are aliasing patterns. Than it might be the correct formula

Artificial Stupidity

1:49 PM

@halirutan Thanks you in advance.

halirutan

2:39 PM

@ArtificialStupidity I believe what you see here is something along Sin[x^2+y^2] but it needs to be damped and combined in a different way.

When you damp it, the small ripples fade out after a while

Plot[Sin[x^2]/x^2, {x, -2 Pi, 2 Pi}]

If you make this now 2d and combine several of these at different places, you get the desired pattern.

Here, I have used only four and the overlapping small ripples create the moire

fc = Compile[{{xx, _Real, 0}, {yy, _Real, 0}}, #,
    CompilationTarget -> "C",
    Parallelization -> True, RuntimeAttributes -> {Listable}] &@
  With[{x = xx - mx, y = yy - my},
   Sum[Exp[-(x^2 + y^2)*1.1]*
     Sin[20 (x^2 + y^2)], {mx, {0, 2}}, {my, {0, 2}}]
   ];

data = Outer[List, #, #] &@Table[x, {x, -1, 3, .001}];

Image[Abs[fc @@ Transpose[data, {3, 2, 1}]]]

Ugly hacked code for the above