#include <stdio.h>
#include <math.h>
#include <stdlib.h>

main(int argc, char *argv[])
{
  int itermax = 100;    /* maximum iters to do */
  double breakout=64.;  /* z^2 greater than this is a breakout */
  double magnify=0.75;    /* 10 is standard magnification  */
  double cr,ci;
  double x0=.09950;
  double y0=-.00062;
  int hxres = 500;    /* horizontal resolution    */
  int hyres = 500;    /* vertical resolution    */
  double x,xx,y,xl,yl,zsq,zm,rb;
  int iter,hx,hy;
  int red,green,blue;
  FILE *ofp;

  rb=sqrt(breakout);
  ofp=fopen("julia.ppm","w");
  if (argc>1) sscanf(argv[1],"%lf",&magnify); 
  if (argc>2) sscanf(argv[2],"%d",&itermax); 
  if (argc>3) sscanf(argv[3],"%lf",&cr); 
  if (argc>4) sscanf(argv[4],"%lf",&ci); 
  if (argc>5) sscanf(argv[5],"%lf",&x0); 
  if (argc>6) sscanf(argv[6],"%lf",&y0); 
  /* header for PPM output */
  fprintf(ofp,"P6\n# magnify=%lf itermax=%d\n",magnify,itermax);
  fprintf(ofp,"%d %d\n255\n",hyres,hxres);

  for (hy=1;hy<=hyres;hy++)  {
    for (hx=1;hx<=hxres;hx++)  {
      ci = 4*((hyres+1-hy-.5)/hyres-0.5)/magnify+y0;
      cr = 4*((hx-.5)/hxres-0.5)/magnify+x0;
      x=0;
      y=0;
      zm=0;
      for (iter=1;iter<itermax;iter++)  {
        xl=x;
        yl=y;
        xx = x*x-y*y+cr;
        y = 2.0*x*y+ci;
        x = xx;
        zsq=x*x+y*y;
        if (zsq > zm) zm=zsq;
        if (zsq>breakout) break;
      }
      if (iter>=itermax){
        red=0;
        green=255.*zm/breakout;
        blue=255.*zm/breakout;
      }
      else{
        red=255*iter/10;				/* CHANGED */
        green=0;					
        blue=.5*255*iter/10;				/* CHANGED */
      }
      fputc((char)red,ofp);
      fputc((char)green,ofp);
      fputc((char)blue,ofp);
    }
  }
  fclose(ofp);
  system("xv julia.ppm");
}