### BURT 2D

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• 3e
• Posts: 1138

#### BURT 2D

« on: April 14, 2019, 08:30:47 AM »
I've been mucking about with some old code (Amiga) and managed to get one of the plotter functions working in Fragmentarium...

iterate...
Code: [Select]
r=z.x;
i=z.y;
{
a = (r * r - i * i) + r;
b = (r * i + r * i) + i;
m = (a * r - b * i);
n = (r * b + i * a);
r -= m;
i -= n;
if( (r*r+i*i) > EscapeRadius ) break;
}
..just wondering if anyone has seen this before or knows if it has a name
« Last Edit: June 07, 2019, 04:34:52 AM by 3DickUlus »
Resistance is fertile... you will be illuminated!

https://en.wikibooks.org/wiki/Fractals/fragmentarium

• 3e
• Posts: 1142

#### Re: Is there a name for this fractal?

« Reply #1 on: April 14, 2019, 04:35:58 PM »
Image looks like a cubic polynomial Julia set. A quick scan of the code and it does seem to be computing something cubic. Oddly I don't see a Julia seed anywhere, as if it's hard-coded to produce just this one.

#### marcm200

• Fractal Furball
• Posts: 245

#### Re: Is there a name for this fractal?

« Reply #2 on: April 14, 2019, 05:35:22 PM »
After some sheets of calculations it looks like zn+1=-zn3+zn2+zn + 0 (at least my software produces the following image that looks identical to me, although originally it was mirrored left to right).

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #3 on: April 14, 2019, 08:22:15 PM »
Thaks for the input guys

@pauldelbrort there is more code involved but I simplified it to show the base shape when all user inputs are at 0

@marcm200 looks like the exact same image to me

is "cubic julia" an accurate name for this formula ? zn+1=-zn3+zn2+zn1+0 looks like a declining series

looking to name this fragment indicatively
« Last Edit: April 14, 2019, 08:42:27 PM by 3DickUlus »

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #4 on: April 14, 2019, 08:47:06 PM »
...the julia variant at 0, using C.xy in place of +r and +i in the first 2 lines looks like this...

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #5 on: April 14, 2019, 10:47:57 PM »
...at first I thought "of course someone here has explored this before" but the closest thing I found is http://www.fractalforums.com/new-theories-and-research/metabrot/msg77460/#msg77460 post about the "Metabrot" but the above formula, zn+1=-zn3+zn2+zn1+0 , is different.

CubicMeta variant ?

#### marcm200

• Fractal Furball
• Posts: 245

#### Re: Is there a name for this fractal?

« Reply #6 on: April 15, 2019, 08:34:44 AM »
Maybe "Burt's bisector" is a suitable name for the formula?

If one sees the coefficients of the formula as a 4D point where the axis are the singleton polynomials zk (k=0..3) then, just as the point (1,1) is on the angle bisector in the upper right quadrant of the complex plane, (-1,1,1,1) is on the bisector of some 4D "quadrant". And taking the initial letters and naming the 3rd dimension quadrants obviously bottom/top and the 4th before/after leads (after shuffling) to BURT.

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #7 on: April 20, 2019, 07:00:24 AM »
getting some interesting results, wondering if can be "bulbified" ?

#### marcm200

• Fractal Furball
• Posts: 245

#### Re: Is there a name for this fractal?

« Reply #8 on: April 20, 2019, 07:22:35 AM »
"AveragePlusandthenSum.jpg" - very nice image! Would've made a great picture for the image of the month contest - gold from me!

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #9 on: April 20, 2019, 07:31:32 AM »
tnx  "Burt's bisector" sounds good, better than anything I thought of    yeah I got nothin' but "Cubic Meta variant"

will keep messing around with it and maybe come up with something for the contest

• Moderator
• Posts: 614

#### Re: Is there a name for this fractal?

« Reply #10 on: April 23, 2019, 09:03:54 PM »
@3Dickulus Beautiful results!
If your entry is anything like "AveragePlusandthenSum.jpg", I agree with marcm200 and it's gold from me too!
To thine own self be true

• 3e
• Posts: 1138

#### Re: Is there a name for this fractal?

« Reply #11 on: April 24, 2019, 02:39:31 AM »
tytyty  will put that one in next month?

• Moderator
• Posts: 614

#### Re: Is there a name for this fractal?

« Reply #12 on: April 24, 2019, 09:06:28 AM »
It's one of the most beautiful fractals I have seen in a while...

• Posts: 65

#### Re: Is there a name for this fractal?

« Reply #13 on: May 28, 2019, 10:41:04 PM »
I ran it through the fractal interpreter in ManpWIN and found the Mandelbrot equivalent of this Julia Set...

I thought it might be of interest.

ManpWIN is available:

Paul the LionHeart

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