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Summary
Source code
#include <stdio.h>
#include <stdlib.h>
#include <vector>
int main () {
const int dimx = 1024 ; /* Image dimension */
const int dimy = 1024 ;
std :: vector < size_t > I ( dimx * dimy );
for ( int i = 0 ; i < dimx * dimy ; ++ i ) I [ i ] = 0 ;
const double e = 0 ; /* brith and grow */
const double k = 1.2 ; /* Discretization */
const double m = 0 ; /* stability */
const double step = 0.03 ; /* Initial point step */
for ( double oy = -1.0 ; oy <= 1.0 ; oy += step ) {
for ( double ox = -0.7 ; ox <= 1.3 ; ox += step ) {
if ( ox == 0 || oy == 0 ) continue ; /* Avoid origin */
double x = ox ;
double y = oy ;
for ( size_t q = 0 ; q < 100000 ; ++ q ) {
y = y + e * y + k * x * ( x - 1 ) + m * x * y ;
x = x + y ;
if ( fabs ( x ) > 2 || fabs ( y ) > 2 ) break ; /* the map diverge */
double imx = ( x - 0.3 ) * dimx / 2 + dimx / 2 ;
double imy = y * dimy / 2 + dimy / 2 ;
if ( fabs ( x ) > 1e-6 || fabs ( y ) > 1e-6 ) { /* Avoid origin */
int ix = int ( imx + 0.5 );
int iy = int ( imy + 0.5 );
if ( ix >= 0 && ix < dimx && iy >= 0 && iy < dimy )
I [ size_t ( dimx ) * ( dimy - 1 - iy ) + ix ] ++ ;
}
}
}
}
size_t maxd = I [ 0 ]; /* Compute max frequency */
for ( int i = 0 ; i < dimx * dimy ; ++ i )
if ( maxd < I [ i ]) maxd = I [ i ];
FILE * fo = fopen ( "c: \\ temp \\ bogdanov_map2.pgm" , "wb" );
fprintf ( fo , "P5 \n %d %d \n 255 \n " , dimx , dimy );
for ( int i = 0 ; i < dimx * dimy ; ++ i ) {
int v = I [ i ] == 0 ? 0 : int ( 32 + ( 256 - 32 ) * I [ i ] / maxd + 0.5 ); if ( v > 255 ) v = 255 ;
unsigned char b = 255 - ( unsigned char ) v ;
fwrite ( & b , 1 , 1 , fo );
}
fclose ( fo );
return 0 ;
}
Licensing
I, the copyright holder of this work, hereby publish it under the following license:
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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. https://creativecommons.org/licenses/by-sa/4.0 CC BY-SA 4.0 Creative Commons Attribution-Share Alike 4.0 true true English Example of Bogdanov map, with e=0, k=1.2, m=0
File history
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Date/Time Thumbnail Dimensions User Comment
current 12:03, 13 May 2020 489 × 375 (78 KB) Rocchini Uploaded own work with UploadWizard
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