public void minus( Point3D_F64 a , Point3D_F64 b ) {
		x = a.x - b.x;
		y = a.y - b.y;
		z = a.z - b.z;
	}
public void minus ( Point3D_F64 a , Point3D_F64 b ) { x = a . x - b . x ; y = a . y - b . y ; z = a . z - b . z ; }
In-place minus operation. this = a - b.

@param a Point
@param b Point