File:Parabolic Julia set for internal angle 1 over 3.png
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Summary
DescriptionParabolic Julia set for internal angle 1 over 3.png |
English: Parabolic Julia set for internal angle 1/3 = fat Douady rabbit. Parameter c is a root point between period 1 and period 3 components of Mandelbrot set. Equivalent maps:
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Date | |
Source | Own work |
Author | Adam majewski |
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Summary
C src code
/*
c console program
-----------------------------------------
1.ppm file code is based on the code of Claudio Rocchini
http://en.wikipedia.org/wiki/Image:Color_complex_plot.jpg
create 8 bit color graphic file , portable graymap file = PGM
see http://en.wikipedia.org/wiki/Portable_pixmap
to see the file use external application ( graphic viewer)
I think that creating graphic can't be simpler
---------------------------
2. first it creates data array which is used to store 1 byte color values of pixels,
fills tha array with data and after that writes the data (array) to binary pgm file in one step.
It alows free ( non sequential) acces to "pixels"
-------------------------------------------
Adam Majewski fraktal.republika.pl
Sobel filter
Gh = sum of six values ( 3 values of matrix are equal to 0 ). Each value is = pixel_color * filter_coefficients
gcc e.c -lm -Wall -O2
gcc e.c -lm -Wall -march=native
./a.out
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <complex.h>
#include <string.h>
/* iXmax/iYmax = 11/13 */
#define iSide 1000
#define iXmax (iSide) /* height of image in pixels */
#define iYmax (iSide)
/* fc(z) = z*z + c */
#define denominator 3 /* denominator of internal angle */
//c = c = -0.125000000000000 +0.649519052838329 i okres = 10000
//
//t= 1/denominator
//t *= (2*PI); // from turns to radians
//cx = 0.5*cos(t) - 0.25*cos(2*t);
//cy = 0.5*sin(t) - 0.25*sin(2*t);
#define Cx -0.125000000000000 /* C = Cx + Cy*i */
#define Cy 0.649519052838329
#define AR PixelWidth /* radius of circle around attractor ZA = target set for attracting points */
#define AR2 (AR*AR)
//#define alfa (1-sqrt(1-4*Cx))/2 /* attracting or parabolic fixed point z = alfa */
//#define beta (1+sqrt(1-4*Cx))/2 /* repelling or parabolic fixed point z = beta */
/* escape time to infinity */
int GiveExtLastIteration(double _Zx0, double _Zy0,double C_x, double C_y, int iMax, double _ER2)
{
int i;
double Zx, Zy;
double Zx2, Zy2; /* Zx2=Zx*Zx; Zy2=Zy*Zy */
Zx=_Zx0; /* initial value of orbit */
Zy=_Zy0;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
for (i=0;i<iMax && ((Zx2+Zy2)<_ER2);i++)
{
Zy=2*Zx*Zy + C_y;
Zx=Zx2-Zy2 +C_x;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
};
return i;
}
/* find attractor ZA using forward iteration of critical point Z = 0 */
/* if period is >1 gives one point from attracting cycle */
double complex GiveAttractor(double _Cx, double _Cy, double ER2, int _IterationMax)
{
int Iteration;
double Zx, Zy; /* z = zx+zy*i */
double Zx2, Zy2; /* Zx2=Zx*Zx; Zy2=Zy*Zy */
/* -- find attractor ZA using forward iteration of critical point Z = 0 */
Zx=0.0;
Zy=0.0;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
for (Iteration=0;Iteration<_IterationMax && ((Zx2+Zy2)<ER2);Iteration++)
{
Zy=2*Zx*Zy + _Cy;
Zx=Zx2-Zy2 + _Cx;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
};
return Zx+Zy*I;
}
/* attracting time to finite attractor ZA */
int GiveIntLastIteration(double _Zx0, double _Zy0,double C_x, double C_y, int iMax, double _AR2, double _ZAx, double _ZAy )
{
int i;
double Zx, Zy; /* z = zx+zy*i */
double Zx2, Zy2; /* Zx2=Zx*Zx; Zy2=Zy*Zy */
double d, dX, dY; /* distance from z to Alpha */
Zx=_Zx0; /* initial value of orbit */
Zy=_Zy0;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
dX=Zx-_ZAx;
dY=Zy-_ZAy;
d=dX*dX+dY*dY;
for (i=0;i<iMax && (d>_AR2);i++)
{
Zy=2*Zx*Zy + C_y;
Zx=Zx2-Zy2 +C_x;
Zx2=Zx*Zx;
Zy2=Zy*Zy;
dX=Zx-_ZAx;
dY=Zy-_ZAy;
d=dX*dX+dY*dY;
};
return i;
}
/* gives position of point (iX,iY) in 1D array ; uses also global variables */
unsigned int f(unsigned int _iX, unsigned int _iY)
{return (_iX + (iYmax-_iY-1)*iXmax );}
/* --------------------------------------------------------------------------------------------------------- */
int main(){
unsigned int iX,iY, /* indices of 2D virtual array (image) = integer coordinate */
i, /* index of 1D array */
iLength = iXmax*iYmax;/* length of array in bytes = number of bytes = number of pixels of image * number of bytes of color */
/* world ( double) coordinate = parameter plane*/
const double ZxMin=-1.3;
const double ZxMax=1.3;
const double ZyMin=-1.3;
const double ZyMax=1.3;
double PixelWidth=(ZxMax-ZxMin)/iXmax;
double PixelHeight=(ZyMax-ZyMin)/iYmax;
/* */
double Zx, Zy; /* Z=Zx+Zy*i */
double complex ZA; /* atractor ZA = ZAx + ZAy*i */
/* */
const double EscapeRadius=2.0; /* radius of circle around origin; its complement is a target set for escaping points */
double ER2=EscapeRadius*EscapeRadius;
const int IterationMax=60,
IterationMaxBig= 100000001;
int eLastIteration, iLastIteration;
/* sobel filter */
unsigned char G, Gh, Gv;
/* color */
unsigned char color[]={255,230,200,180,150}; /* shades of gray used in image */
const unsigned int MaxColorComponentValue=255; /* color component is coded from 0 to 255 ; it is 8 bit color file */
/* dynamic 1D arrays for colors ( shades of gray ) */
unsigned char *data, *edge;
data = malloc( iLength * sizeof(unsigned char) );
edge = malloc( iLength * sizeof(unsigned char) );
if (data == NULL || edge==NULL)
{
fprintf(stderr," Could not allocate memory");
getchar();
return 1;
}
else printf(" memory is OK\n");
/* */
ZA = GiveAttractor( Cx, Cy, ER2, IterationMaxBig); /* find attractor ZA using forward iteration of critical point Z = 0 */
printf(" fill the data array \n");
for(iY=0;iY<iYmax;++iY){
Zy=ZyMin + iY*PixelHeight; /* */
if (fabs(Zy)<PixelHeight/2) Zy=0.0; /* */
printf(" row %u from %u \n",iY, iYmax);
for(iX=0;iX<iXmax;++iX){
Zx=ZxMin + iX*PixelWidth;
eLastIteration = GiveExtLastIteration(Zx, Zy, Cx, Cy, IterationMax, ER2 );
i= f(iX,iY); /* compute index of 1D array from indices of 2D array */
if ( IterationMax != eLastIteration )
{data[i]=245;} /* exterior */
else /* interior */
{ iLastIteration = GiveIntLastIteration(Zx, Zy, Cx, Cy, IterationMaxBig, AR2, creal(ZA), cimag(ZA));
data[i]=color[iLastIteration % denominator];} /* level sets of attraction time */
/* if (Zx>0 && Zy>0) data[i]=255-data[i]; check the orientation of Z-plane by marking first quadrant */
}
}
printf(" find boundaries in data array using Sobel filter\n");
for(iY=1;iY<iYmax-1;++iY){
for(iX=1;iX<iXmax-1;++iX){
Gv= data[f(iX-1,iY+1)] + 2*data[f(iX,iY+1)] + data[f(iX-1,iY+1)] - data[f(iX-1,iY-1)] - 2*data[f(iX-1,iY)] - data[f(iX+1,iY-1)];
Gh= data[f(iX+1,iY+1)] + 2*data[f(iX+1,iY)] + data[f(iX-1,iY-1)] - data[f(iX+1,iY-1)] - 2*data[f(iX-1,iY)] - data[f(iX-1,iY-1)];
G = sqrt(Gh*Gh + Gv*Gv);
i= f(iX,iY); /* compute index of 1D array from indices of 2D array */
if (G==0) {edge[i]=255;} /* background */
else {edge[i]=0;} /* boundary */
}
}
// printf(" copy boundaries from edge to data array \n");
// for(iY=1;iY<iYmax-1;++iY){
// for(iX=1;iX<iXmax-1;++iX)
// {i= f(iX,iY); /* compute index of 1D array from indices of 2D array */
// if (edge[i]==0) data[i]=0;}}
/* ---------- file -------------------------------------*/
printf(" save data array to the file \n");
FILE * fp;
char name [10]; /* name of file */
i = sprintf(name,"pw%2.9f",AR); /* result (is saved in i) but is not used */
char *filename =strcat(name,".pgm");
char *comment="# C=0.2";/* comment should start with # */
/* save image to the pgm file */
fp= fopen(filename,"wb"); /*create new file,give it a name and open it in binary mode */
fprintf(fp,"P5\n %s\n %u\n %u\n %u\n",comment,iXmax,iYmax,MaxColorComponentValue); /*write header to the file*/
fwrite(edge,iLength,1,fp); /*write image data bytes to the file in one step */
printf("File %s saved. \n", filename);
fclose(fp);
/* --------------free memory ---------------------*/
free(data);
free(edge);
return 0;
}
Captions
Parabolic Julia set for internal angle 1/3 = fat Douady rabbit
Items portrayed in this file
depicts
some value
7 October 2012
image/png
File history
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Date/Time | Thumbnail | Dimensions | User | Comment | |
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current | 07:41, 7 October 2012 | ![]() | 1,000 × 1,000 (11 KB) | Soul windsurfer | {{Information |Description ={{en|1=Parabolic Julia set for internal angle 1 over 4 = fat Douady Rabbit}} |Source ={{own}} |Author =Adam majewski |Date =2012-10-07 |Permission = |other_versions =Fi... |
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