#include <math.h>

#include "mathutils.h"

#include "2darith.h"

double xylength(XY v)
{
 return(hypot(v.x,v.y));
}

double dot2(XY a, XY b)
{
 return((a.x*b.x)+(a.y*b.y));
}

XY xyscale(XY v, double s)
{
 return((XY){v.x*s,v.y*s});
}

XY xysub(XY a, XY b)
{
 return((XY){a.x-b.x,a.y-b.y});
}

XY xyadd(XY a, XY b)
{
 return((XY){a.x+b.x,a.y+b.y});
}

XY xyunit(XY v)
{
 return(xyscale(v,1/xylength(v)));
}

XY xyrotate(XY v, double a)
{
 double s;
 double c;

 s = sindeg(a);
 c = cosdeg(a);
 return((XY) { (v.x * c) - (v.y * s),
	       (v.y * c) + (v.x * s) });
}

XY xyrotatecw(XY v)
{
 return((XY){v.y,-v.x});
}

XY xyrotateccw(XY v)
{
 return((XY){-v.y,v.x});
}

XY xy_subtract_component(XY v, XY u)
{
 return(xysub(v,xyscale(u,dot2(v,u))));
}

XY xyblend(XY a, double f, XY b)
{
 return( (XY) { ((1-f) * a.x) + (f * b.x),
		((1-f) * a.y) + (f * b.y) } );
}

double zcross(XY a, XY b)
{
 return((a.x*b.y)-(a.y*b.x));
}