/* 
   Simulation of the discrete logistic map.

   x[i+1] = h*x[i](1.0 - x[i])

   Last Modified: August 23, 1999 by Bill Goodwine 
*/

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

main(int argc, char *argv[]) {

  int i,steps;
  double x,h;
  char str[255];
  FILE *fp;

  if(argc != 4) { 
    printf("Usage: %s h xinit steps\n",*argv); 
    exit(1); 
  } 

  h = atof(argv[1]);
  x = atof(argv[2]);    
  steps = atoi(argv[3]);

  fp = fopen("cobweb.d","w");
  fprintf(fp,"%f\t%f\n%f\t%f\n\n\n",0.0,0.0,1.0,1.0);
  fprintf(fp,"%f\t%f\n",x,0.0);

  for(i=0;i<=steps;i++) {
    fprintf(fp,"%f\t%f\n%f\t%f\n",x,x*h*(1-x),x*h*(1-x),x*h*(1-x));
    x = x*h*(1-x);
  }     
  fclose(fp);

  strcpy(&str[0],"gnuplot <<EOF
set terminal postscript eps
set output 'logistic.eps'
set nokey
set title 'h =");
  strcat(&str[0],argv[1]); 
  strcat(&str[0],"\nset xrange[0:1]\nplot x*(1-x)*");
  strcat(&str[0],argv[1]); 
  strcat(&str[0],", 'cobweb.d' with lines\n");
  strcat(&str[0],"set output 'timeseries.eps'\nset xrange[*:*]\n");
  strcat(&str[0],"plot 'cobweb.d' index 1 every 2 using 1\nEOF\n"); 
  
  system(str); 
  system("ghostview logistic.eps &");
  system("ghostview timeseries.eps &");
  system("\\rm cobweb.d");
}