// This generates a circle. d = 2.
#include <math.h>
#include "l.h"
#include <stdlib.h>
bp g2(int vc){R* a = malloc(sizeof(R)*vc*2);
  short * l = malloc(sizeof(short)*vc*2);
  R const tpi = 2.*3.1415926535897932385;
  {int j=vc; while(j--) {
     a[2*j] = cos(j*tpi/vc); a[2*j+1] = sin(j*tpi/vc);
     l[2*j] = j; l[2*j+1] = j+1;}
   l[2*(vc-1)+1] = 0;}
return (bp){2, vc, a, vc, l};}

static R wh[] = {1, -1}; static short c[] = {0, 1};
bp g1(){return (bp){1, 2, wh, 2, c};}

// routine gx returns a zero brane with a boundary.
// This is helpful in debugging.
bp gx(){return (bp){1, 1, wh+1, 1, c};}