嗯..我也來release一下....

[Picard (我要一百分)]

        拿來練習BGI做的，logistic mapping的程式，請見笑。
        (Comments不是我不加，我要去準備量物啦！)
        (出現BGI不能啟始的，請自己改一下initgraph的path。)

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

int Take_five(double input)
{
 if(input>639.5)
 {
  closegraph();
  printf("input= %f\n",input);
  printf("The point which to draw exceeds the maximum resolution!!\n");
  exit(-1);
 }
 else
 {
  if((input-(int)input)>=0.5)
        return (int)input+1;
  else
        return (int)input;
 }
}

void main(void)
{
 int i,N=5000,
     graphdriver,
     graphmode;
 double a=3.3,
        X,Y,dX=5E-5,
        X_0=0.4,X_N,X_N_1;
 printf("Enter iteration N= ");
 scanf("%d",&N);
 printf("Enter a= ");
 scanf("%lf",&a);
 printf("Enter initial X_0= ");
 scanf("%lf",&X_0);

 detectgraph(&graphdriver,&graphmode);
 initgraph(&graphdriver,&graphmode,"D:\\Turbo-C\\");
 setbkcolor(WHITE);

 setcolor(GREEN);
 line(0,0,0,479);
 line(0,479,639,479);

 for(X=0;X<=1;X+=dX)
 {
  Y=a*X*(1-X);
  putpixel(Take_five(X*639),Take_five(479-Y*479),RED);
 }

 X_N=X_0;
 X_N_1=a*X_N*(1-X_N);
 line(Take_five(X_N*639),479,Take_five(X_N*639),Take_five(479-X_N_1*479));
 for(i=0;i<=N;i++)
 {
  setcolor(i%14+1);
  line(Take_five(X_N*639),Take_five(479-X_N_1*479),Take_five(X_N_1*639),
       Take_five(479-X_N_1*479));
  X_N=X_N_1;
  X_N_1=a*X_N*(1-X_N);
  line(Take_five(X_N*639),Take_five(479-X_N*479),Take_five(X_N*639),
       Take_five(479-X_N_1*479));
 }

 printf(" N= %d\n a= %f\n X_0= %f",N,a,X_0);
 getch();
 closegraph();
}

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