#include <stdio.h>
#include <stdlib.h>
#include <X11/Xlib.h>
#include <X11/Xutil.h>
#include <X11/Xos.h>
#include <X11/Xatom.h>
#include <X11/keysym.h>
#include<math.h>
Display *dis;
Window win;
XEvent report;
GC green_gc;
XColor green_col;
Colormap colormap;
char green[] = "#00FF00";

void rect()
{ //XDrawRectangle(dis, win, green_gc, 1, 1, 497, 497);
  //XDrawRectangle(dis, win, green_gc, 50, 50, 398, 398);
  XFlush(dis);
}

double f(double x)
{ static double phi=(1+sqrt(5.0))/2; // -2cos(4pi/5)
  if(0) return x*x;
  if(0) return x<0?0:-x; // périodique de période 7
  if(0) return x<0?0:x; // périodique de période 5
  if(0) return x*(1+x);
  if(0) return x*(1+x)/2-1;  // (0,1) de période 4
  if(0) return x*(x/1000-1); // diverge
  if(0) return x/(x-1); // 3 courbes
  if(0) return x*(x*x*x/9999-phi); // coquillage
  if(0) return x*(x*x*x*x*x/999+2*cos(M_PI*2/7)); // coquillage
  if(0) return 2*cos(M_PI*2/5)*x/(1-x*x*x); // 5 pétales
  if(0) return 2*cos(M_PI*2/7)*x/(1-x*x*x*x*x); // 7 pétales
  if(0) return (x>0?x*x:0)-x;  // 13 boucles
  if(0) return x*(x-1)/2; // (0,1) -> courbe d'indice 2  avec 7 trous
  if(0) return x*(x-1)/3;
  if(0) return x*(2*x-1)/4;
  if(0) return x*(x+1)/2; // (0,1) -> de période 5, entouré d'anneaux qui se permutent  (0,0.773291) -> courbe d'indice 2
  if(0) return x*(1-x*x)/6; // (0,1) -> 2 courbes avec 4 trous
  if(0) return 1/(1+x*x);
  if(0) return 1/(1+x*x)-1;
  if(1) return x/(1+x*x);
}
int coord(double x) { return (x+2)/4*500; }  // [-2..2] -> [0..500]
double xini=0, yini=0, dx=0.05;
void nuage()
{ int i,j;
  long double x=xini, y=xini, z;
  for(i=100000;i--;)
  { for(j=1;j--;) z=f(y)-x, x=y, y=z;
    XDrawPoint(dis, win, green_gc, coord(x), coord(y));  // http://www.cuis.edu/doc_vms_html/000000/731final/5642/5642pro_007.html
  }
}

int main() {
  dis = XOpenDisplay(NULL);
  win = XCreateSimpleWindow(dis, RootWindow(dis, 0), 1, 1, 500, 500, 0, BlackPixel (dis, 0), BlackPixel(dis, 0));
  XMapWindow(dis, win);
  colormap = DefaultColormap(dis, 0);
  green_gc = XCreateGC(dis, win, 0, 0);
  XParseColor(dis, colormap, green, &green_col);
  XAllocColor(dis, colormap, &green_col);
  XSetForeground(dis, green_gc, green_col.pixel);

  XSelectInput(dis, win, ExposureMask | KeyPressMask | ButtonPressMask);
  nuage();
  rect();

  for(;;)
  { XNextEvent(dis, &report);
    switch(report.type)
    { case Expose: nuage(),rect(); break;
      case KeyPress: switch(XLookupKeysym(&report.xkey, 0))
      { case 'q': exit(0);
        case 'p': xini+=dx; break;
        case 'm': xini-=dx; break;
        case 'h': dx/=2; break;
        case 't': dx*=2; break;
        case 'd': nuage(); break;
        case 'r': printf("x=%lf x=",xini),scanf("%lf",&xini); break;
        case 'w': printf("x=%lf \n",xini); break;
      }
    }
  }
  return 0;
}