File:Bogdanov map.png
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Bogdanov_map.png (489 × 375 pixels, file size: 78 KB, MIME type: image/png)
This file is from Wikimedia Commons and may be used by other projects. The description on its file description page there is shown below.
Summary
| DescriptionBogdanov map.png |
English: Bogdanov map : |
| Date | |
| Source | Own work |
| Author | Claudio Rocchini |
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\n255\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
Claudio Rocchini, the copyright holder of this work, hereby publishes it under the following license:
This file is licensed under the Creative Commons Attribution-Share Alike 4.0 International license.
Attribution:
- 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.
Captions
Example of Bogdanov map, with e=0, k=1.2, m=0
Items portrayed in this file
depicts
some value
13 May 2020
image/png
8e545f7434065bbad248ba7bc4e9d95cb5b0e1b3
79,805 byte
375 pixel
489 pixel
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 13:03, 13 May 2020 | 489 × 375 (78 KB) | wikimediacommons>Rocchini | Uploaded own work with UploadWizard |
File usage
The following page uses this file:
Retrieved from "https://en.wiki.beta.math.wmflabs.org/wiki/File:Bogdanov_map.png"
