File:Amoeba2.png
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Summary
| Description | The amoeba of P(z, w)=3z2+5zw+w3+1 |
| Date | 28 February 2007 (original upload date) |
| Source | Own work |
| Author | Oleg Alexandrov |
|
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Licensing
|
I, the copyright holder of this work, release this work into the public domain. This applies worldwide. In some countries this may not be legally possible; if so: I grant anyone the right to use this work for any purpose, without any conditions, unless such conditions are required by law. |
C++ code
#include <iostream>
#include <fstream>
#include <cmath>
#include <complex>
using namespace std;
double small = 1e-14;
double mylog (double);
int main(){
double A=-5, B=5;
int N=1000;
double h= (B-A)/(N-1);
double theta0 = 2*M_PI/(N-1.0);
ofstream mfile ("data.txt");
for (int i=0 ; i < N ; i++){
double r = exp(A+i*h);
for (int j=0 ; j < N ; j++){
double theta = j*theta0;
complex<double> z2 = polar(r, theta);
complex<double> root = sqrt(25.0*z2*z2-12.0*(z2*z2*z2+1.0));
complex<double> z11 = (-5.0*z2+root)/6.0;
complex<double> z12 = (-5.0*z2-root)/6.0;
double a1 = mylog(abs(z11));
double a2 = mylog(abs(z12));
double b = mylog(abs(z2));
mfile << a1 << ' ' << b << endl;
mfile << a2 << ' ' << b << endl;
}
}
mfile.close();
return 0;
}
double mylog (double x){
if (x< 0){
cerr << "Error in log, negative x!" << endl;
exit(0);
}
if (x < small){
return log (small);
}
return log (x);
}
Matlab code which reads the data output by the C++ code and graphs it
A=load('data.txt');
plot(A(:, 1), A(:, 2), '.');
axis equal; axis off;
axis([-4 6 -5 5])
saveas(gcf, 'amoeba2.eps', 'psc2');
File history
Click on a date/time to view the file as it appeared at that time.
| Date/Time | Thumbnail | Dimensions | User | Comment | |
|---|---|---|---|---|---|
| current | 04:22, 9 March 2007 | | 1,504 × 1,446 (13 KB) | Oleg Alexandrov | |
| 04:42, 28 February 2007 |  | 1,078 × 1,092 (28 KB) | Oleg Alexandrov | ||
| 04:17, 28 February 2007 |  | 1,078 × 1,081 (40 KB) | Oleg Alexandrov | Made by myself with matlab. |
File usage
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