question: public static ResultSet polar2Cartesian ( Double r , Double alpha ) { SimpleResultSet rs = new SimpleResultSet ( ) ; rs . addColumn ( "X" , Types . DOUBLE , 0 , 0 ) ; rs . addColumn ( "Y" , Types . DOUBLE , 0 , 0 ) ; if ( r != null && alpha != null ) { double x = r . doubleValue ( ) * Math . cos ( alpha . doubleValue ( ) ) ; double y = r . doubleValue ( ) * Math . sin ( alpha . doubleValue ( ) ) ; rs . addRow ( x , y ) ; } return rs ; }
target:  Convert polar coordinates to cartesian coordinates. The function may be called twice, once to retrieve the result columns (with null parameters), and the second time to return the data.