發送短信 : The ψS polar decomposition when the cosquare of S is normal

  ______    _____     _  _     ______    ______  
 /_____//  |  ___||  | \| ||  /_   _//  /_   _// 
 `____ `   | ||__    |  ' ||   -| ||-   `-| |,-  
 /___//    | ||__    | .  ||   _| ||_     | ||   
 `__ `     |_____||  |_|\_||  /_____//    |_||   
 /_//      `-----`   `-` -`   `-----`     `-`'   
 `-`