main/src/georegression/metric/Distance2D_F64.java
public static double distance2(EllipseRotated_F64 ellipse , Point2D_F64 p ) {
		// put point into ellipse's reference frame
		double cphi = Math.cos(ellipse.phi);
		double sphi = Math.sin(ellipse.phi);

		double xc = p.x - ellipse.center.x;
		double yc = p.y - ellipse.center.y;
		double r = Math.sqrt(xc*xc + yc*yc);

		double x =  cphi*xc + sphi*yc;
		double y = -sphi*xc + cphi*yc;

		double ct = x/r;
		double st = y/r;

		x = ellipse.center.x + ellipse.a*ct*cphi - ellipse.b*st*sphi;
		y = ellipse.center.y + ellipse.a*ct*sphi + ellipse.b*st*cphi;

		return p.distance2(x,y);
	}
public static double distance2(EllipseRotated_F64 ellipse , Point2D_F64 p ) {
		// put point into ellipse's reference frame
		double cphi = Math.cos(ellipse.phi);
		double sphi = Math.sin(ellipse.phi);

		double xc = p.x - ellipse.center.x;
		double yc = p.y - ellipse.center.y;
		double r = Math.sqrt(xc*xc + yc*yc);

		double x =  cphi*xc + sphi*yc;
		double y = -sphi*xc + cphi*yc;

		double ct = x/r;
		double st = y/r;

		x = ellipse.center.x + ellipse.a*ct*cphi - ellipse.b*st*sphi;
		y = ellipse.center.y + ellipse.a*ct*sphi + ellipse.b*st*cphi;

		return p.distance2(x,y);
	}
public static double distance2 ( EllipseRotated_F64 ellipse , Point2D_F64 p ) { // put point into ellipse's reference frame double cphi = Math . cos ( ellipse . phi ) ; double sphi = Math . sin ( ellipse . phi ) ; double xc = p . x - ellipse . center . x ; double yc = p . y - ellipse . center . y ; double r = Math . sqrt ( xc * xc + yc * yc ) ; double x = cphi * xc + sphi * yc ; double y = - sphi * xc + cphi * yc ; double ct = x / r ; double st = y / r ; x = ellipse . center . x + ellipse . a * ct * cphi - ellipse . b * st * sphi ; y = ellipse . center . y + ellipse . a * ct * sphi + ellipse . b * st * cphi ; return p . distance2 ( x , y ) ; }
Euclidean distance squared of closest point on ellipse to point 'p'.

@param ellipse Ellipse
@param p Point
@return Euclidean distance squared
Euclidean distance squared of closest point on ellipse to point p .