Tetration fractal (C++ with TBB)

tetration_tbb.cpp

#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <cstdlib>
#include <cmath>
#include <sys/time.h>

#include "tbb/task_scheduler_init.h"
#include "tbb/parallel_for.h"
#include "tbb/blocked_range.h"
#include "tbb/tick_count.h"

using namespace std;
using namespace tbb;

const double PI = 3.1415926535897931;

// Tetration fractal
class Tetration {
private:
    float l, t, w, h;
    int sw, sh, mit;
    vector<int>& data;

public:
    // left, top, width , height, screen width, screen height, max iterations, data[sw*sh]
    Tetration(float l, float t, float w, float h, int sw, int sh, int mit, vector<int>& data)
        : l(l), t(t), w(w), h(h), sw(sw), sh(sh), mit(mit), data(data) { }

    void operator()(const blocked_range<int>& r) const {
        for (int n = r.begin(); n != r.end(); n++) {
            float x = l + w * (n % sw) / (sw - 1);
            float y = t + h * (n / sw) / (sh - 1);
            int i = 0;
            for (; i < mit - 1; i++) {
                float e = exp(-0.5 * PI * y);
                if (e != e) break;
                float p = PI * x * 0.5;
                x = e * cos(p);
                y = e * sin(p);
                if (x * x + y * y > 1e12) break;
            }
            data[n] = i;
        }
    }
};

int main(int argc, char* argv[])
{
    if (argc < 6) {
        cerr << "Usage: " << argv[0] << " outfile left top width height [screen_width=512 screen_height=512 max_iters=256]" << endl;
        cerr << "  Ex. " << argv[0] << " tetration.out -1.5 0.0 0.75 0.75" << endl;
        exit(1);
    }

    task_scheduler_init init;

    fstream fs(argv[1], ios_base::out);
    float l = atof(argv[2]);
    float t = atof(argv[3]);
    float w = atof(argv[4]);
    float h = atof(argv[5]);

    int sw = 512;
    int sh = 512;
    int mit = 256;
    if (argc >= 7) sw = atoi(argv[6]);
    if (argc >= 8) sh = atoi(argv[7]);
    if (argc >= 9) mit = atoi(argv[8]);

    vector<int> data(sw * sh);

    cout << "Range: (" << l << ", " << t << ") - (" << l + w << ", " << t + h << ")" << endl;
    cout << "Image: " << sw << " x " << sh << endl;
    cout << "Max number of iterations: " << mit << endl;

    tick_count start_time = tick_count::now();
    parallel_for(blocked_range<int>(0, sw * sh), Tetration(l, t, w, h, sw, sh, mit, data), auto_partitioner());
    cout << "Time: " << (tick_count::now() - start_time).seconds() << endl;

    // output data
    int cnt = 0;
    fs << sw << " " << sh << endl;
    for (vector<int>::iterator p = data.begin(); p != data.end(); ++p, cnt++) {
        fs << *p << " ";
        if ((cnt + 1) % sw == 0) fs << endl;
    }

    return 0;
}

http://handasse.blogspot.com/2012/05/blog-post.html