Koch Curve

/*
Koch Curve

*/

#include 
#include 
#include 

/*Random Number*/
#define IA 16807
#define IM 2147483647
#define AM (1.0/IM)
#define IQ 127773
#define IR 2836
#define NTAB 32
#define NDIV (1+(IM-1)/NTAB)
#define EPS 1.2e-7
#define RNMX (1.0-EPS)

unsigned long int idum =1024;

float ran1(long *);

main()
{
  int j; /*j;step number*/
  double x=1.0,nx=0.0;
  double y=0.0,ny=0.0;
  double r=0.0;

  for(j=0;j<=100000;j++)
    {
      r=ran1(&idum);

      if (r >= 0.5){
	nx=0.5*x+y*1.7320501/6.0;
	ny=x*1.7320501/6.0-0.5*y;
        }
      else if (r < 0.5){
	nx=0.5*x-y*1.7320501/6.0+0.5;
	ny=-x*1.7320501/6.0-0.5*y+1.7320501/6.0;
        }

	printf("%f %f\n",nx, ny);
	/*printf("%d %f\n",j, nx);*/
    x=nx;
    y=ny;
    }
  return 0;
}

float ran1(long *idum)
{
  int j;
  long k;
  static long iy=0;
  static long iv[NTAB];
  float temp;
  
  if(*idum <= 0 || !iy){
    if(-(*idum) < 1) *idum =1;
    else *idum = -(*idum);
    for (j=NTAB +7;j>=0; j--){
      k=(*idum)/IQ;
      *idum=IA*(*idum-k*IQ)-IR*k;
      if (*idum < 0) *idum += IM;
      if( j < NTAB) iv[j]=*idum;
    }
    iy=iv[0];
  }
  k=(*idum)/IQ;
  *idum=IA*(*idum-k*IQ)-IR*k;
  if (*idum < 0) *idum += IM;
  j=iy/NDIV;
  iy=iv[j];
  iv[j]= *idum;
  if((temp=AM*iy) > RNMX) return RNMX;
  else  return temp;
}
出力結果
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