#define VORONOI_NSITES 9


Point circ_center(delaunay_site_t *a, delaunay_site_t *b, delaunay_site_t *c)
  {
    Point ctr;

    double px[3], py[3];
    double dx[3], dy[3], mx[3], my[3], q[3];
    double det[3], rx[3], ry[3];
    double swx, swy, sw;
    int i, j;
    
    px[0] = ((double) a->p.c[0]); py[0] = ((double) a->p.c[1]); 
    px[1] = ((double) b->p.c[0]); py[1] = ((double) b->p.c[1]); 
    px[2] = ((double) c->p.c[0]); py[2] = ((double) c->p.c[1]); 
    
    for (i=0; i<3; i++)
      { j = (i==2 ? 0 : i+1);
        dx[i] = px[j] - px[i];
        dy[i] = py[j] - py[i];
        mx[i] = (px[j] + px[i])/2.0;
        my[i] = (py[j] + py[i])/2.0;
        q[i] = dx[i]*mx[i] + dy[i]*my[i];
      }
      
    swx = 0.0; swy = 0.0; sw = 0.0;

    for (i=0; i<3; i++)
      { j = (i==2 ? 0 : i+1);
        det[i] = dx[i]*dy[j] - dx[j]*dy[i];
        rx[i] = q[i]*dy[j] - q[j]*dy[i];
        ry[i] = dx[i]*q[j] - dx[j]*q[i];
        swx += det[i] * rx[i];
        swy += det[i] * ry[i];
        sw += det[i] * det[i];
        /*
          fprintf(stderr, 
            "circ_center: xc = %f yc = %f det = %f\n", 
            rx[i]/det[i], ry[i]/det[i], det[i]
          );
        */
      }
      
    fprintf(stderr, "\n");
        
    ctr.c[0] = swx/sw;
    ctr.c[1] = swy/sw;
    return (ctr);
  }


    sites[0] = (site_struct){-0.750, +0.575};
    sites[1] = (site_struct){-0.050, +0.525};
    sites[2] = (site_struct){+0.700, +0.750};
    sites[3] = (site_struct){-0.650, -0.075};
    sites[4] = (site_struct){+0.075, +0.000};
    sites[5] = (site_struct){+0.525, +0.175};
    sites[6] = (site_struct){-0.450, -0.375};
    sites[7] = (site_struct){+0.575, -0.425};
    sites[8] = (site_struct){+0.225, -0.725};
    affirm(n == 9, "makesites: bad n");

    sites[0] = (site_struct){-0.750, +0.575};
    sites[1] = (site_struct){-0.050, +0.525};
    sites[2] = (site_struct){+0.700, +0.750};
    sites[3] = (site_struct){-0.650, -0.075};
    sites[4] = (site_struct){+0.075, +0.000};
    sites[5] = (site_struct){+0.525, +0.175};
    sites[6] = (site_struct){-0.450, -0.375};
    sites[7] = (site_struct){+0.575, -0.425};
    sites[8] = (site_struct){+0.225, -0.725};
    affirm(n == 9, "makesites: bad n");

    sites[0] = (site_struct){-0.750, +0.575};
    sites[1] = (site_struct){-0.050, +0.525};
    sites[2] = (site_struct){+0.700, +0.750};
    sites[3] = (site_struct){-0.650, -0.075};
    sites[4] = (site_struct){+0.075, +0.000};
    sites[5] = (site_struct){+0.525, +0.175};
    sites[6] = (site_struct){-0.450, -0.375};
    sites[7] = (site_struct){+0.575, -0.425};
    sites[8] = (site_struct){+0.225, -0.725};
    affirm(n == 9, "makesites: bad n");

void relnei_makesites (int n, site_struct sites[])
  {
    sites[ 0] = (site_struct){-0.750, +0.575};
    sites[ 1] = (site_struct){-0.050, +0.525};
    sites[ 2] = (site_struct){+0.700, +0.750};
    sites[ 3] = (site_struct){-0.650, -0.075};
    sites[ 4] = (site_struct){+0.325, +0.000};
    sites[ 5] = (site_struct){+0.525, +0.175};
    sites[ 6] = (site_struct){-0.400, -0.450};
    sites[ 7] = (site_struct){+0.575, -0.425};
    sites[ 8] = (site_struct){+0.225, -0.725};
    sites[ 9] = (site_struct){-0.325, +0.350};
    sites[10] = (site_struct){+0.500, +0.510};
    sites[11] = (site_struct){-0.250, -0.075};
    affirm(n == 12, "makesites: bad n");
  }