{--------------------------------------------}
{UE10. 2006. UNSA.          }
{  Modele discrets : Courbe logistique       }
{--------------------------------------------}



program Verhulst;

Uses Crt, Graph, GRAPH2D;

const Lim = 7;

var R, X, N : real;
    I,K : integer;

BEGIN

   clrscr;
   write ('Valeur de R ( 0<=R<=3) : ');
   readln (R);
   EcranGraphique;
   Fenetre (0, Lim, -0.1, 1.5);
   Cloture (100, 800, 100, 800);
   Axes;
   Gradue (10, 0.1);
   N := 0;
   X := 0.1;
   K := 1;
   setcolor(red);
   DeplaceEn (N, X);

   repeat
      N := N+ 0.1;
      X := (1 + R) * X - R * sqr(X)/K;
      TraceVers (N, X);
   until N > Lim;

   repeat until KeyPressed;
   EcranTexte;
END.