MandelBrot Set

#include <stdio.h>
#include <math.h>
#include <fcntl.h>
#include <stdlib.h>
void color();

main()
{
    int k;
    int fd;
    char buffer[100];

    double x,xx,y,cx,cy;
    int iteration,hx,hy;
    int itermax = 100;      /* how many iterations to do    */
    double magnify=1.0;     /* no magnification     */
    int hxres = 1500;       /* horizonal resolution     */
    int hyres = 1500;       /* vertical resolution      */

    char pic[hyres][hxres][3];

    /* header for PPM output */
    printf("%d %d\n255\n",hxres,hyres);

    for (hy=1;hy<=hyres;hy++)  {
        for (hx=1;hx<=hxres;hx++)  {
            cx = (((float)hx)/((float)hxres)-0.5)/magnify*3.0-0.7;
            cy = (((float)hy)/((float)hyres)-0.5)/magnify*3.0;
            x = 0.000001; y = 0.000001;
            for (iteration=1;iteration<itermax;iteration++)  {
                xx = x*x-y*y+cx;
                y = 2.0*x*y+cy;
                x = xx;
                if (x*x+y*y>100.0){
                    iteration = 9999999;
                    int inset = 0;
                    k = iteration;
                }
            }
            if (iteration<9999999){
                color(35,0,0);
                pic[hy][hx][0] = 0;
                pic[hy][hx][1] = 0;
                pic[hy][hx][2] = 0;
            }
            else {
                color(42,0,0);
                pic[hy][hx][0] = k * 255;
                pic[hy][hx][1] = k * 255 / 2;
                pic[hy][hx][2] = k * 255 / 2;
            }
        }
    }

  if ((fd = open("mand.tga", O_RDWR+O_CREAT, 0)) == -1)
  {
    printf("error opening file\n");
    exit(1);
  }
  buffer[0] = 0;
  buffer[1] = 0;
  buffer[2] = 2;
  buffer[8] = 0; buffer[9] = 0;
  buffer[10] = 0; buffer[11] = 0;
  buffer[12] = (hxres & 0x00FF); buffer[13] = (hxres & 0xFF00) >> 8;
  buffer[14] = (hyres & 0x00FF); buffer[15] = (hyres & 0xFF00) >> 8;
  buffer[16] = 24;
  buffer[17] = 0;
  write(fd, buffer, 18);
  write(fd, pic, hxres*hyres*3);
  close(fd);
}

void color(int red, int green, int blue)  {
    fputc((char)red,stdout);
    fputc((char)green,stdout);
    fputc((char)blue,stdout);
}