main/src/georegression/geometry/UtilPlane3D_F64.java
public static void hessianNormalForm( PlaneGeneral3D_F64 plane ) {
		double n = Math.sqrt(plane.A*plane.A + plane.B*plane.B + plane.C*plane.C);
		plane.A /= n;
		plane.B /= n;
		plane.C /= n;
		plane.D /= n;
	}
public static void hessianNormalForm( PlaneGeneral3D_F64 plane ) {
		double n = Math.sqrt(plane.A*plane.A + plane.B*plane.B + plane.C*plane.C);
		plane.A /= n;
		plane.B /= n;
		plane.C /= n;
		plane.D /= n;
	}
Converts the plane into Hessian normal form.   This is done by dividing each coefficient by the
Euclidean norm of (A,B,C).

@param plane The input plane.  Modified.