#ifndef _2DARITH_H_2da539ad_
#define _2DARITH_H_2da539ad_

typedef struct xy XY;

struct xy {
  double x;
  double y;
  } ;

extern double xylength(XY);
extern double dot2(XY, XY);
extern XY xyscale(XY, double);
extern XY xysub(XY, XY);
extern XY xyadd(XY, XY);
extern XY xyunit(XY);
extern XY xyrotate(XY, double);
extern XY xyrotatecw(XY);
extern XY xyrotateccw(XY);
extern XY xyrotate180(XY);
extern XY xy_subtract_component(XY, XY);
extern XY xyblend(XY, double, XY);
extern double zcross(XY, XY);

#endif