public static TransformMatrix2D rotate(double alpha){
  final double sin=Math.sin(alpha);
  final double cos=Math.cos(alpha);
  return new TransformMatrix2D(cos,sin,-sin,cos,0.0d,0.0d);
}

public static TransformMatrix2D rotate ( double alpha ) { final double sin = Math . sin ( alpha ) ; final double cos = Math . cos ( alpha ) ; return new TransformMatrix2D ( cos , sin , - sin , cos , 0.0d , 0.0d ) ; }
produces a transformation matrix representing a rotation operation around the origin of the coordinate system .
