File:Parabolic critical orbits.png

Original file(1,000 × 500 pixels, file size: 11 KB, MIME type: image/png)

Summary

Description
English: Parabolic [1]critical orbits for points on boundary of period 1 hyperbolic component of Mandelbrot set for internal angles from 1/1 to 1/10. Because critical orbit tends to fixed point very slowly there is a gap between critical orbit and fixed point.
Date
Source Own work with help of Mario Rodríguez Riotorto [2]
Author Adam majewski

Summary

There are 3 types of points here :

  • blue = critical point
  • red = critical orbit ( forward orbit of critical point )
  • black = parabolic fixed point ( critical orbit tends to this point )

Because :

  • there are only 5000 points of critical orbit on each diagram ( iMax:5000; )
  • critical orbit tends to fixed point very slowly

on some images there is a gap between critical orbit and fixed point.

One can also see that :

  • the gap is directly proportional to denominator of internal angle
  • speed of attraction is directly proportional to internal angle

Here are some example values computed in C program ( note that i is double type not integer, because of integer limits ):

iWidth  = 1001 // width of image in pixels
PixelWidth  = 0.003996  
AR  = 0.003996 // Radius around attractor
denominator  = 1 ; Cx  = 0.250000000000000; Cy  = 0.000000000000000 ax  = 0.500000000000000; ay  = 0.000000000000000   
denominator  = 2 ; Cx  = -0.750000000000000; Cy  = 0.000000000000000 ax  = -0.500000000000000; ay  = 0.000000000000000   
denominator  = 3 ; Cx  = -0.125000000000000; Cy  = 0.649519052838329 ax  = -0.250000000000000; ay  = 0.433012701892219  
denominator  = 4 ; Cx  = 0.250000000000000; Cy  = 0.500000000000000 ax  = 0.000000000000000; ay  = 0.500000000000000   
denominator  = 5 ; Cx  = 0.356762745781211; Cy  = 0.328581945074458 ax  = 0.154508497187474; ay  = 0.475528258147577   
denominator  = 6 ; Cx  = 0.375000000000000; Cy  = 0.216506350946110 ax  = 0.250000000000000; ay  = 0.433012701892219    

denominator  = 1 ;   i =               243.000000 
denominator  = 2 ;   i =            31 171.000000 
denominator  = 3 ;   i =         3 400 099.000000 
denominator  = 4 ;   i =       333 293 206.000000 
denominator  = 5 ;   i =    29 519 565 177.000000 
denominator  = 6 ;   i = 2 384 557 783 634.000000 

where :

C = Cx + Cy*i 
a = ax + ay*i // fixed point alpha
i // number of iterations after which critical point z=0.0 reaches disc around fixed point alpha with radius AR
denominator of internal angle =  1/denominator

Note that attraction time i is proportional to denominator.

Now you see what means weakly attracting.

Licensing

I, the copyright holder of this work, hereby publish it under the following license:
w:en:Creative Commons
attribution share alike
This file is licensed under the Creative Commons Attribution-Share Alike 3.0 Unported license.
You are free:
  • to share – to copy, distribute and transmit the work
  • to remix – to adapt the work
Under the following conditions:
  • attribution – You must give appropriate credit, provide a link to the license, and indicate if changes were made. You may do so in any reasonable manner, but not in any way that suggests the licensor endorses you or your use.
  • share alike – If you remix, transform, or build upon the material, you must distribute your contributions under the same or compatible license as the original.

Maxima CAS src code

Newest code

/* thx to Mario Rodriguez Riotorto www.biomates.net */
kill(all);

/* ---------- functions ---------------------- */

/* conformal map  from circle to cardioid ( boundary
 of period 1 component of Mandelbrot set */
F(w):=w/2-w*w/4;

/* 
circle D={w:abs(w)=1 } where w=l(t,r) 
t is angle in turns ; 1 turn = 360 degree = 2*Pi radians 
r is a radius 
*/
ToCircle(t,r):=r*%e^(%i*t*2*%pi);

/* 

http://en.wikipedia.org/wiki/Complex_quadratic_polynomial 
*/
f(z,c):=z*z+c $

GiveCriticalOrbit(c,iMax):=
   /* 
   computes (without escape test)
   critical orbit (forward orbit of critical point )
   and saves it to the list for draw package */
block(
 [z,orbit,temp],
 z:0, /* first point = critical point z:0+0*%i */
 orbit:[[realpart(z),imagpart(z)]], 
 for i:1 thru iMax step 1 do
        ( z:expand(f(z,c)),
          orbit:endcons([realpart(z),imagpart(z)],orbit)),
         
 return(orbit) 
)$

/* find fixed point alfa , returns a list */
GiveFixed(c):= 
(
 [z],
z:float(rectform((1-sqrt(1-4*c))/2)),
[[realpart(z),imagpart(z)]]
)$

GiveC(angle,radius):=
(
 [w],
 /* point of  unit circle   w:l(internalAngle,internalRadius); */
 w:ToCircle(angle,radius),  /* point of circle */
 float(rectform(F(w)))    /* point on boundary of period 1 component of Mandelbrot set */
)$

GiveScene(sTitle, zn, orbitn):=
gr2d(title= sTitle,
	user_preamble = "set border 0;set nokey;set size square;set noxtics ;set noytics;",
	
        point_type    = filled_circle,
	points_joined = false,
        point_size    = 0.7,
        /* critical orbit */
	color		  =red,
	points(orbitn),
        /* parabolic fixed point */
	color		  =black,
	point_size    = 1.4,
	points(zn),
        /* criitical point */
	color		  =blue,
	points([0],[0])
        )$

compile(all)$

/* ---------- constant ---------------------------*/
Numerator :1;
DenominatorMax :10;
InternalRadius:1;
iMax:500;

/* -------------- main ----------------- */ 

scenes:[];
for Denominator:1 thru DenominatorMax step 1 do
(
 InternalAngle: Numerator/Denominator,
 c: GiveC(InternalAngle,InternalRadius),
 scene:GiveScene(string(InternalAngle), GiveFixed(c), GiveCriticalOrbit(c,iMax)),
 scenes:cons(scene,scenes))$

/*-----------------------------------------------------------------------*/
load(draw); /* ( interface to gnuplot ) by Mario Rodriguez Riotorto http://www.telefonica.net/web2/biomates */

draw(
    
    terminal  = screen,
    columns =5,
    file_name = "b",
    pic_width  = 1000,    /* Since Maxima 5.23, pic_width and pic_height are deprecated. */
    pic_height = 500,    /* See option dimensions. To get the same effect, write dimensions=[800,600] */

    scenes

 );

References

  1. parabolic dynamics
  2. Mario Rodríguez Riotorto

Captions

Add a one-line explanation of what this file represents

Items portrayed in this file

depicts

22 January 2012

File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current00:12, 22 January 2012Thumbnail for version as of 00:12, 22 January 20121,000 × 500 (11 KB)Soul windsurfer